Mohs Micrographic Surgery: From Layers to Reconstruction E-Book

Christopher B. Harmon

• Herausgeber: Thieme
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 655

Veröffentlichungsjahr: 2023

Beschreibung

A systematic approach to Mohs surgery and reconstruction from renowned skin cancer surgeons 

More than 5.4 million cases of nonmelanoma skin cancer, most notably basal cell and squamous cell carcinoma, and melanoma, occur annually in the United States alone. The Mohs technique, developed in the 1950s and refined over the years, has the highest cure rate of any treatment for nonmelanoma skin cancer, is used increasingly for melanoma, and has the lowest recurrence rate. Mohs Micrographic Surgery: From Layers to Reconstruction by renowned dermatologic and Mohs surgeons Christopher Harmon and Stanislav Tolkachjov provides a detailed yet succinct road map to learning and mastering Mohs and reconstruction.

The algorithmic organization coupled with instructive photographs and illustrations provide a reader-friendly format conducive to learning. The two opening chapters describe the principles of Mohs surgery including progressive layer excision to determine if wound margins are cancer free, associated pitfalls, recurrences, special sites, reconstructive principles, and general considerations. The subsequent eight chapters are organized by facial site, from the nose to the eyelid/eyebrow. The final two chapters discuss combination reconstructions stretching over multiple subunits and perioperative management and wound care.

Key Highlights

• An impressive group of global Mohs and reconstruction experts provide firsthand pearls that guide optimal treatment
• Relevant anatomical aspects that impact excision and reconstruction are detailed, including structures, skin tension lines, tissue planes, and dangers zones
• More than 20 procedural videos provide hands-on guidance on how to perform specific steps in Mohs and reconstruction

This unique resource will help residents, fellows, and surgeons in dermatology, plastic surgery, and facial plastic surgery master nuances of Mohs reconstructive techniques to achieve the most functional and aesthetically pleasing outcomes for patients.

This book includes complimentary access to a digital copy on https://medone.thieme.com

Leseprobe

To access the additional media content available with this e-book via Thieme MedOne, please use the code and follow the instructions provided at the back of the e-book.

Mohs Micrographic Surgery: From Layers to Reconstruction

Christopher B. Harmon, MD, FAAD, FACMS Dermatologic Surgeon Surgical Dermatology Group; Director ACGME Fellowship in Micrographic Surgery and Dermatologic Oncology Birmingham, Alabama, USA

Stanislav N. Tolkachjov, MD, FAAD, FACMS Dermatologic Surgeon and Dallas-Fort Worth Area Director Mohs Micrographic & Reconstructive Surgery Epiphany Dermatology; Clinical Assistant Professor University of Texas Southwestern Medical Center; Clinical Associate Professor Texas A&M College of Medicine; Core Faculty Division of Dermatology Baylor University Medical Center Dallas, Texas, USA

813 illustrations

ThiemeStuttgart • New York • Delhi • Rio de Janeiro

Library of Congress Cataloging-in-Publication Data is available from the publisher.

© 2023 Thieme. All rights reserved.

Georg Thieme Verlag KG Rüdigerstrasse 14, 70469 Stuttgart, Germany +49 [0]711 8931 421, [email protected]

Cover design: © ThiemeCover image source: © ThiemeTypesetting by DiTech Process Solutions Pvt. Ltd., India

Printed in Germany by Beltz Grafische Betriebe                    5 4 3 2 1

DOI: 10.1055/b000000239

ISBN 978-3-13-242017-5

Also available as an e-book:eISBN (PDF): 978-3-13-242018-2eISBN (epub): 978-3-13-258252-1

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To begin with, I am grateful to my uncle, Dr. John Yarbrough, for his influence to pursue surgical dermatology as a career path over cardiovascular surgery and other surgical subspecialties. “Unc” (as hewas affectionately referred to) gave me an appreciation for the art and relational aspect of medicine that supersedes the science of medicine. More than anyone I’ve known, John had a skill for connecting with patients and compassionately providing care. In his words, “With the frailty of one human being helping another human being…we practice medicine.” He was indeed inclined to treat rather than not treat. Another favorite quote that he borrowed from Dr. John Voorheeswas, “I’mnot much on diagnosis, but I’m hell on treatment.”

As a lifelong learner, I have had the opportunity to continue to learn from the 25 plus Mohs surgery fellows we have trained over a 20-year period. As they now practice in locations from South Carolina to California, our continued collaboration fosters the sharing of ideas, evolving new surgical concepts, best business practices, and most importantly continued friendship and collegiality. Thank you all for the “rebound mentorship” … keep up the good work.

This text is the result of experience gained from over 80,000 surgical cases in the past 22 years referred to our practice (Surgical Dermatology Group) from the dermatologists and other physicians practicing in Alabama and surrounding states. Your growing friendship over the years is cherished. The vote of confidence you place by entrusting your skin cancer patients to our care is our life blood.We value the great care you provide for your patients and thank you for the opportunity to participate in their care.

I could not have succeeded with undertakings such as this textbook, or the opening of new office locations, and the highvolume of surgical caseswe performwithout our “Surgical Dermatology Group” team members. Fromphysicians to mid-levels and executive team members, to the Ambulatory Surgery Center RNs, CRNAs, our histotechnicians and medical assistants, aswell as surgery schedulers, receptionists, and back-office support staff…thank you all for doing what you do with humility and a commitment to excellence.

Formy parents…thank you for providing a homelife that encourages progress and an unending pursuit of excellence. This foundation of love, approval, and support has culminated in this writing and in any successes I have experienced. Ultimately, I dedicate thiswork tomy wife Sandy and our two daughters, Mary Elizabeth andHaley, for supportingmy various career endeavors like the undertaking of a textbook which intrudes evenings andweekends. They are the joy of my life and the reason I do what I do…whether on the tennis court, the mission field, or over prayer time at the dinner table.

Christopher B. Harmon, MD, FAAD, FACMS

To the Almighty God, throughWhom all things are possible andWhose will be done. You give us strength when we have none. You lift us up whenwe are at our depths. You use our hands and the talents You have given us to do Your healing. Your Son made the ultimate sacrifice, so we can forever be with You.

Tomy selfless and loving wife, Holly. You have stood beside me on the journey from when medicinewas just a dream. Youhave accomplished somuchyet stepped back to allowme tochasemy dreams.Youhavebeen a pillar for our family and a beautiful example of enduring love. You’re an incredibly strong individual yet an altruistic best friend. I love you for you.

Tomy children, Alexander and Ekaterina. Many of the long hours spent on this project I took from you. Every moment spent with you fuels and recharges my soul. There’s nothing more precious than watching you grow up loving each other, your family, and theworld around you. Your spirit of empathy, honesty, idealism, love, enthusiasm, humor, fun, and care are examples I bring to treatmy patients daily. May our bonds continue to growand may you growup to be a shining light and a helping hand to the world around you. You are and will always be our greatest achievement.

Tomy mother and Brian. You brought me from Russia at a young age.We survived on little to nothing, but you taught me the value of hard work, education, and sacrifice. You gave up your dreams for a better life for me. I love you.

Stanislav N. Tolkachjov, MD, FAAD, FACMS

Contents

Videos

Foreword

Preface

Acknowledgments

Contributors

1Mohs Micrographic Surgery

1.1Before the First Stage

Nicholas Golda and George Hruza

1.1.1Tumor Selection

1.1.2Documentation of Site

1.1.3Time-Out

1.2Procedures before the First Stage

Nicholas Golda and George Hruza

1.2.1Curettage

1.2.2Sharp Debulking

1.3The First Stage

Nicholas Golda and George Hruza

1.3.1Essentials of the First Stage

1.3.2Incomplete Excision and Recurrence

1.4Tissue Processing

Nicholas Golda and George Hruza

1.4.1Tissue Transfer

1.4.2Relaxing Incisions and Dividing

1.4.3Tissue Inking

1.5Histologic Interpretation/Mapping

Nicholas Golda and George Hruza

1.5.1Initial Slide Quality Review

1.5.2Histologic Interpretation

1.5.3Tissue Mapping

1.6Subsequent Layers

Nicholas Golda and George Hruza

1.6.1Subsequent LayersWhen Malignancy is Present Only in the Deep Tissue

1.7Nonstandard Situations

Nicholas Golda and George Hruza

1.8Mohs Layers in Special Sites

Thomas Hocker

1.8.1Eyelid

1.8.2Lip

1.8.3Ear

1.8.4Nose

1.8.5Periosteum/Bone

1.8.6Nail

1.8.7Anogenital Region

2Facial Subunit Reconstructive Principles and General Considerations

Christopher J. Miller, Joseph F. Sobanko, Nicole Howe, Thuzar Shin, Jeremy R. Etzkorn, and H. William Higgins II

2.1Design Principles of Facial Reconstruction

2.1.1Overview

2.1.2Free Margins

2.1.3Contour

2.1.4Cosmetic Subunit Junction Lines

2.1.5Relaxed Skin Tension Lines

2.1.6Color and Texture

2.2Principles of Tissue Biomechanics

2.2.1Overview

2.2.2Preferred Vectors to Move Facial Tissue

2.2.3How Different Reconstructions Affect Location of Tension Relative to the Primary Defect

2.2.4Tissue Planes for Undermining and Elevating Flaps

2.3Key Principles of Anatomy

2.3.1Overview

2.3.2Blood Supply to the Face

2.3.3Superficial Musculoaponeurotic System

2.4Systematic Approach to Assessing FacialWounds and Choosing Reconstruction

2.4.1Overview

2.4.2DefineWhat Is Missing

2.4.3Prioritize Principles for Reconstruction Design

2.4.4Choose among Reconstruction Options

2.5Reconstruction Options for Facial Reconstruction

2.5.1Overview

2.5.2Second Intention Healing

2.5.3Linear Closure

2.5.4Skin Grafts

2.5.5Sliding Flaps

2.6Conclusion

3Nose

Evan Stiegel and John Zitelli

3.1Introduction

3.2Anatomy

3.3Nasal Tip

3.3.1Second Intention Healing

3.3.2Primary Closure

3.3.3Bilobed Flap

3.3.4Dorsal Nasal (Rieger’s) Flap

3.3.5Forehead

3.3.6Prelaminated and Prefolded Forehead Flap

3.3.7Conchal Bowl Full-Thickness Skin Graft

3.4Nasal Ala

3.4.1Second Intention

3.4.2Grafts

3.4.3Medial-Based Bilobed Flap

3.4.4Spiral Flap

3.4.5Cheek-to-Nose Interpolation Flap

3.4.6Spear Flap

3.4.7Technique

3.5Soft Triangle/Columella

3.5.1Turnover Flap

3.5.2Nasal Tip Rotation Flap

3.6Nasal Dorsum

3.7Nasal Root/Lower Glabella

3.8Nasal Sidewall

3.8.1Rhombic Transposition Flap

3.8.2Superior-Based Bilobed Flap

3.8.3Lateral-Based Rotation Flap/Crescentic Advancement Flap/Cheek-Based Burow’s Advancement Flap

3.8.4V-Y Flap

3.8.5Single-Stage Nasolabial Flap

3.9Complications and Revisions

4Forehead and Temple Reconstruction

Joseph F. Sobanko, Ashwin Agarwal, and Christopher J. Miller

4.1Forehead and Temple Anatomy

4.1.1Boundaries of the Forehead and Temple Subunits

4.1.2Muscles of the Forehead and Temple

4.1.3Blood Supply to the Forehead and Temple

4.2Preservation of Sensory and Motor Function

4.2.1Sensory Function

4.2.2Motor Function

4.3Achieving Reproducibly Excellent Cosmetic Results

4.4EvaluatingWounds on the Forehead and Temple

4.5Reconstruction Options for the Forehead and Temple

4.5.1Second Intention

4.5.2Linear Closure

4.5.3Local Flaps

4.5.4Sliding Flaps

4.5.5Transposition Flaps

4.5.6Skin Grafts

4.6Complications

4.7Conclusion

5Scalp

David Zloty, Irèn Kossintseva, and Victoria Godinez-Puig

5.1Relevant Anatomy

5.1.1Skin

5.1.2Subcutis

5.1.3Galea Aponeurotica

5.1.4Subgaleal Loose Connective Tissue

5.1.5Periosteum

5.2Reconstructive Options

5.2.1Algorithm for Scalp Reconstruction

5.2.2Second Intention Healing

5.2.3Skin Grafts

5.2.4Local Flaps

5.3Complications

6Cheek

Jonathan Cappel

6.1Introduction

6.2Relevant Anatomy

6.3Aesthetic Subunits and Defects

6.4Reconstructive Options

6.4.1Primary Closures

6.4.2Flaps

6.4.3Second Intention Healing

6.4.4Full-Thickness Skin Graft

6.5Complications and Revisions

7Auricular Reconstruction

David G. Brodland and Molly Powers

7.1Introduction

7.2Relevant Anatomy

7.3Reconstructive Options

7.3.1Superior Helix

7.3.2Mid helix

7.3.3Lobule

7.3.4Antihelix

7.3.5Concha

7.3.6Tragus

7.3.7Remainder of the Posterior Ear

7.4Complications and Revisions

8Lip (Perioral) Reconstruction

Nicola A. Quatrano and Thomas E. Rohrer

8.1Introduction

8.2Cosmetic Subunits and Relevant Anatomy

8.3Reconstructive Algorithm

8.3.1Vermilion

8.3.2Cutaneous Lateral Upper Lip

8.3.3Philtrum

8.3.4Cutaneous Lower Lip

8.4Complications and Revisions.

9Chin Reconstruction

Christopher B. Harmon and Randall Proctor

9.1Relevant Anatomy

9.2Aesthetic Subunits and Defects

9.3Reconstructive Options

9.3.1Algorithm

9.3.2Healing by secondary intention

9.3.3Primary closure

9.3.4Bilateral Advancement (O-T flap)

9.3.5V-Y Advancement Flap

9.3.6Rotation flaps

9.3.7Transposition flaps

9.3.8Full-Thickness Skin Grafts

9.4Complications and Revisions

10Reconstruction of the Eyelids and Eyebrows

Gabriela M. Espinoza and Aleksandar L. Krunic

10.1Introduction

10.2Surgical Anatomy of the Eyelids and Eyebrows

10.2.1Superficial Topography of the Lids and Eyebrows

10.2.2Orbicularis Oculi Muscle (OOM)

10.2.3Orbital Septum (OS) and Postseptal Fat Compartments

10.2.4Tarsoligamentous Sling

10.2.5Eyelid Retractors

10.2.6Conjunctiva

10.2.7Lacrimal System

10.2.8Neurovascular and Lymphatic System of the Lids

10.2.9Orbit

10.2.10Eyebrow Anatomy

10.3Principles and Aims of Periocular Reconstruction

10.4Perioperative Surgical Tips, Instrumentations, and Sutures in Periocular Reconstruction

10.5Surgical Assessment of the Periocular Defect and Reconstruction Guidelines

10.6Secondary Intention Healing

10.7Grafts in Periocular Reconstruction

10.8Repair of Superficial Nonmarginal Eyelid Defects

10.9Reconstruction of the Full-Thickness Eyelid Defects

10.9.1Primary Closure of the Full-Thickness Defects of the Eyelids

10.9.2Semicircular Flap (Tenzel)

10.9.3Tarsoconjunctival Flap for Lower Eyelid Reconstruction (Hughes Flap)

10.9.4Tarsal Transposition Flap for Lateral Upper Eyelid Reconstruction

10.9.5Cutler-Beard Flap for Complete Upper Eyelid Reconstruction

10.10Lower Lid Tightening Procedures

10.11Wound Dressing and Postoperative Care in Periocular Surgery Patients

10.12Lacrimal Canalicular System Assessment and Reconstruction

10.13Complications of Eyelid Reconstructions

10.14Aims and Principles of Eyebrow Reconstruction

10.14.1Primary Closure of Brow Defects

10.14.2Advancement Flaps

10.14.3Island-Pedicle Flaps

10.14.4Transposition Flaps

10.14.5Pedicle Flaps

10.14.6Free Hair-Bearing Grafts (Composite Grafts—Skin and Hair)

10.15Conclusion

11Combination Reconstruction

Stanislav N. Tolkachjov

11.1Introduction

11.2Combination of Primary and Graft Reconstruction

11.2.1Arm/Hand

11.2.2Temple

11.2.3Cheek

11.3Combination of Flap and Graft Reconstruction

11.3.1Lateral Infraocular Cheek

11.3.2Periauricular Cheek/Ear

11.3.3Upper Cutaneous Lip/Philtrum/Alar Sill

11.3.4Medial Cheek/Nasal Sidewall

11.3.5Forehead/Temple

11.3.6Large Nasal Defects

11.4Combination of Flaps for Reconstruction of Single and Multiple Defects

11.4.1Large Nasal Defects

11.4.2Lip

11.5Reconstruction of Multiple Defects

11.5.1Multiple Defects Repaired as One

11.5.2“West by East-West”

11.5.3O-T Advancement Flap, Scalp/Forehead Rotation Flap, and Paramedian Forehead Flap

11.5.4“Combo-Z” Flap

11.5.5Multiple Defects Repaired with Burow’s Grafts

11.5.6The “Kitchen Sink”:When Combination Reconstruction and Granulation Gets Us Out of a Jam

11.6Summary

12Perioperative Management andWound Care

Jason R. Castillo, Jennifer L. Hanson, and Randall K. Roenigk

12.1Preoperative Considerations

12.1.1Antibiotic Prophylaxis

12.1.2Anticoagulants

12.1.3Conscious Sedation/Analgesia

12.1.4Implantable Devices

12.2Postoperative Care

12.2.1Granulation/Second-Intention Healing

12.2.2Porcine Xenografts and Biologic Dressings

12.2.3Bolster Sutures

12.2.4Postdermabrasion Care

12.2.5Postprimary Closure on the Lower Extremity

12.2.6Postflap Care

12.3Hematoma Management

12.4Infection Management

12.4.1Infection

12.4.2Antimicrobial Selection

12.5Pain Management

Index

Videos

Video 1.1:

Curettage following sharp debulking.

Video 1.2:

Sharp debulking—eyelid.

Video 1.3:

Excising the first stage during Mohs surgery.

Video 1.4:

Forceps-free atraumatic Mohs initial stage.

Video 1.5:

Basic first-stage tissue processing.

Video 1.6:

Subsequent Mohs stages.

Video 1.7:

Sampling the hinge point on subsequent Mohs stages.

Video 1.8:

Deep layer epidermal tag technique.

Video 1.9:

Deep layer postage stamp technique.

Video 1.10:

Gridding for deep only layers.

Video 1.11:

Initial and subsequent stages.

Video 3.1:

Shave and sand technique.

Video 3.2:

Bilobed flap.

Video 3.3:

Forehead flap.

Video 3.4:

Conchal bowl full-thickness skin graft.

Video 3.5:

Nasolabial flap.

Video 7.1:

Helical rim advancement.

Video 7.2:

Flip flop flap.

Video 8.1:

Repair of a large cutaneous lateral upper lip defect with a crescentic advancement flap. (Courtesy of Stanislav N. Tolkachjov, MD.)

Video 10.1:

Snap test.

Video 10.2:

Full-thickness skin graft with blepharoplasty incision lower eyelid defect.

Video 10.3:

Semicircular Tenzel’s flap.

Video 10.4:

Insertion and removal of corneal protective shields.

Video 11.1:

Combo-Z (neck).

Video 11.2:

Combo-Z (temple).

Video 12.1:

Bolster suture.

Foreword

I believe that this book is an indispensable addition to educational resources vital to developing andmaintaining the skill set essential to the practice ofMohs surgery, fromlayers to reconstruction. Experience of 30 years as a Mohs and reconstructive surgeon has given me a strong appreciationfor the importance ofbuildingupon the foundation thatwe all acquire through our training. Throughout these years, teaching and participating in the education of other physicians has been a big part of myprofessional activities.Whether educating residents as the Program Director at the Mayo Clinic and later as clinical staff of the University of Pittsburgh, or directing our Micrographic Surgery and Dermatologic Oncology fellowships, the educational resources have always beencritical components inproviding young physicians a proper foundation. But continuing education for the more experienced practitioner is no less vital to the quality of care provided to patients with skin cancer. Our patients benefit most from a skin surgeon with a solid academic education and who continues to seek new, improved approaches and who assimilates creative nuances in the reconstruction of wounds. After serving as the Program Chair for the annual meeting of the Mohs College in 1999, it became even more evident to me that ongoing education is valuable for all skin surgeons. Since 1999, I have been privileged to serve as Section Editor of the “Reconstruction Conundrums” feature in Dermatologic Surgery, whichprovides new and creative approaches to common and not-socommon cutaneous defects. Through these experiences, I have found that the bottom line in optimizing care for patients with skin cancer through education is to understand that young surgeons yearn for thoughtful, well-reasoned structure for their reconstructive armamentariumand more seasoned operators continue to seek new and creative techniques to handle common and rare reconstructive challenges.

This handbook caters to all.

Dr. Chris Harmon and Dr. Stan Tolkachjov are the perfect team to accomplish the arduous task of formulating a comprehensive book of reconstructions. For the two of them, I knowitwas a labor of love. Chris, with his quarter century of experience in a highvolume skin cancer practice and whose mastery of Mohs surgery and the aesthetics of reconstruction, underpinned by an exceptionally strong background in cosmetic surgery, is ideally suited for this task. He has been involved for many years in the education of young surgeons through his fellowship training program and through continuous involvement in the educational programs at the most prominent national meetings on dermatology. He has a calm, thoughtful approach to life in general, but particularly in the realm of reconstruction that will be manifest in this textbook.

Stan, on the other hand, is the perfect complement to Chriswithhisyouthful enthusiasm.Butdon’tbefooledby his youth. Stan is years beyond his age in the understanding of reconstructive surgery and of the importance of a structural yet creative resource for the practicing skin cancer surgeon. He has an intimate understanding of what is essential to a young surgeon’s development. Together, Chris and Stan are the perfect duo for engineering this important vessel of knowledge.

This textbook is important to skin surgeons because it organizes the specific knowledge needed for competent execution of cancer removal followed by the reconstruction of the defects … and it does so succinctly, with the busy practitioner in mind. It’s easy-to-follow format features algorithmic organization complemented by instructive photographs, videos, and illustrations. In short, readers will benefit from the experienced ingenuity of the premiere group of experts who Chris and Stan have assembled to author chapters and who have written about a subject they are passionate about. Their passion is evident in these chapters and will inspire and guide both the younger surgeons and the experienced practitioners who read this book. The chapters herein represent hundreds of hours of preparation and tens of thousands of hours of experience. This collective effort is masterfully organized and condensed for those who choose to spend a fewhours absorbing its contents.On behalf of patients with skin cancer across the world and for their sake, I hope that this book becomes a major resource for many, many skin cancer surgeons.

David G. Brodland, MD Zitelli & Brodland Skin Cancer Center; Assistant Professor Departments of Dermatology, Otolaryngology and Plastic Surgery, University of Pittsburgh Pittsburgh, Pennsylvania, USA

Preface

Aswe submit this manuscript to our publisher,we are in the midst of theCOVID-19 pandemic. However, for a longer period of time we have been experiencing a skin cancer epidemic globally and in the US. This is primarily because the oldest of the “baby boomers” are now aging beyond 65. Over the next 20 years, as this bolus of population continues to have birthdays into their 80s and 90s,we will see the incidence of skin cancer rise above the current one in five Americans. This context provides the backdrop for what compels us to publish this book…to share knowledge with our peers today and future generations of dermatologists, Mohs surgeons, and reconstructionists.We are grateful to be working in the field of dermatology, specializing in the removal of skin cancers with the highest curative rates available. The technique of Mohs surgery, developed by Dr. Fred Mohs in the 1950s, has improved over the years, especially with the advent of fresh frozen technique as refined by Stegman and Tromovitch in the 1980s, as noted in their seminal article “Microscopically Controlled Excision of Cutaneous Tumors: Chemosurgery, Fresh Tissue Technique.” Today, micrographic surgery allows us to yield a very high cure rate in the patients we serve. Our approach with Mohs surgery is to eradicate each tumor with the least number of stages while providing the best comfort for our patients and sparing the greatest amount of adjacent healthy tissue. Our goal for reconstruction is a systematic approach for each defect in order to achieve the most functional and aesthetically pleasing results for our patients and their referring physicians.

In this textbook, we have brought together the most reputable and experienced group of Mohs and reconstructive surgeons in the field with an overarching theme of creating the systematic approach to subunit reconstruction and a step-by-step description of reconstructive techniques. Each author was chosen for his/her expertise in the field as well as the specific section or anatomic location. For complete understanding of Mohs surgery, we have included chapters on the Mohs technique, how the process is adapted in difficult anatomic locations, preoperative/postoperative considerations, flap and reconstructive mechanics, and “combination reconstructions” stretching over multiple subunits. It is well illustrated and easily implemented in the daily practice.

This book is a complete, yet succinct, guide to Mohs micrographic surgery and reconstruction with the practicing Mohs and facial reconstructive surgeon in mind.

Christopher B. Harmon, MD, FAAD, FACMSStanislav N. Tolkachjov, MD, FAAD, FACMS

Acknowledgments

For me personally, this project is a privileged collaboration with mentors and colleagues who represent many of the best surgeons within our specialty. As a dermatology resident at Mayo Clinic in Rochester, Minnesota, both Dr. Randy Roenigk and Dr. Dave Brodland provided mentorship and training that set a trajectory for my career. It is indeed a privilege to have them both contributing to this textbook. Following residency, I had a 3-year Air Force commitment which took me to Keesler Air Force Base in Biloxi, Mississippi, where I continued to do Mohs surgery with another mentor, Dr. Rick Mora. During those 3 years I also had an opportunity to spend several 1-week rotations in Pittsburg working with Dr. John Zitelli and again Dr. Dave Brodland… further learning surgical techniques before entering a Mohs fellowship.

Following my service in the Air Force, I moved to Birmingham, Alabama, to do a Mohs College sponsored fellowship with Dr. Gary Monheit. I then practiced with Dr. Monheit as a partner for the next 12 years. To this day, much of what we do in our current practice mirrors the surgery, scheduling, workflow, and business acumen I learned during my years with him … for this I am indebted.

Lastly, Dr. Stan Tolkachjov, a former fellow and practice partner, unequivocally gets credit for being the impetus behind this textbook. His encouragement to undertake the project and his desire to be a handson contributing editor were the spark I needed to get this meaningful work underway. The collaborative nature of the text gave me an opportunity to partner with both more senior mentors as described above, and younger contemporaries. Stan and I both feel very fortunate to pull together such an austere group of surgeons and authors. To Stan and the other authors—I am grateful for your contributions and proud of the collaborative work represented here.

Christopher B. Harmon, MD, FAAD, FACMS

I acknowledge the hard work of former and current medical assistants, nurses, histotechnicians, former fellows, and other colleagues in spending time and effort in taking photographs and videos, helping in surgery, obtaining patient consents, and most importantly, taking excellent care of patients. I acknowledge Elizabeth Bryant for help in coordinating these efforts early in the book’s inception.

I acknowledge the guidance in fellowship of Dr. Christopher Harmon in learning Mohs surgery and reconstructive techniques and confidence to perform any reconstruction.We believe in being excited about the biggest and most difficult tumors to help patients and improve upon each surgery with an open mind and heart of service. Iwould also like to thank him for partnering with me on this book.

I greatly appreciate the work of Preston McDonald and Chelsea Decker for help in editing the videos and the funding assistance of Gherghe Pusta and Epiphany Dermatology for video editing.

Lastly, I want to thank my patients for kindly allowing us to use their photographs and images to teach generations of surgeons and improve patient care for others. I also thank my referring providers for entrusting us with their patients. Without our patients and referring providers, this dream would not be possible.

Stanislav N. Tolkachjov, MD, FAAD, FACMS

Contributors

Ashwin Agarwal, MD Department of Dermatology Perelman School of Medicine University of Pennsylvania Philadelphia, Pennsylvania, USA

David G. Brodland, MD Zitelli & Brodland Skin Cancer Center; Assistant Professor Departments of Dermatology, Otolaryngology and    Plastic Surgery, University of Pittsburgh Pittsburgh, Pennsylvania, USA

Jonathan Cappel, MD Surgical Dermatology Group Birmingham, Alabama, USA

Jason R. Castillo, MD Micrographic Surgery and Dermatologic Oncology    Fellow Mayo Clinic Rochester, Minnesota, USA

Gabriela M. Espinoza, MD Associate Professor Program Director Ophthalmology, Plastic and Reconstructive Surgery Saint Louis University St. Louis, Missouri, USA

Jeremy R. Etzkorn, MD Assistant Professor of Dermatology Hospital of the University of Pennsylvania Philadelphia, Pennsylvania, USA

Victoria Godinez-Puig, MD, FAAD, FACMS VitalSkin Chicago, Illinois, USA

Nicholas Golda, MD Associate Professor of Dermatology Dermatology Medical Director Micrographic Surgery and Dermatologic Oncology    Program Director University of Missouri School of Medicine Columbia, Missouri, USA

Jennifer L. Hanson, MD, FAAD Vitalogy Skincare Georgetown, Texas, USA

Christopher B. Harmon, MD, FAAD, FACMS Dermatologic Surgeon Surgical Dermatology Group; Director ACGME Fellowship in Micrographic Surgery and    Dermatologic Oncology Birmingham, Alabama, USA

H. William Higgins II, MD, MBE Assistant Professor of Dermatology Penn Dermatology Oncology Center University of Pennsylvania Philadelphia, Pennsylvania, USA

Thomas Hocker, MD Advanced Dermatologic Surgery, P.A. ADS Ambulatory Surgery Center Overland Park, Kansas, USA

Derek T. Cawley, MMedSc, MCh, FRCS Orth Novem Dermatology Lutz, Florida, USA

George Hruza, MD, MBA, FAAD Adjunct Professor of Dermatology St. Louis University St. Louis, Missouri, USA; Laser & Dermatologic Surgery Center Chesterfield, Missouri, USA

Irèn Kossintseva, MD, FRCPC, FAAD, FACMS Associate Professor Dermatologic Surgery Centre Department of Dermatology and Skin Sciences University of British Columbia Vancouver, British Columbia, Canada

Aleksandar L. Krunic, MD, PhD, FAAD, FACMS, FEADV, FESMS Adjunct Associate Professor of Dermatology Rush University Medical Center; Director of Dermatologic Surgery Cook County Hospital Health System; Health Clinician Northwestern University Feinberg School of Medicine; Chicago, Illinois, USA

Christopher J. Miller, MD Director of Dermatologic Surgery Hospital of the University of Pennsylvania Philadelphia, Pennsylvania, USA

Molly Powers, MD Henry Ford Medical Center Novi, Michigan, USA

Randall Proctor, Jr, MD, MBA, FACMS Eastern Dermatology & Pathology, PA Greenville, North Carolina, USA

Nicola A. Quatrano, MD SkinCare Physicians Chestnut Hill, Massachusetts, USA

Randall K. Roenigk, MD Professor of Dermatology Director of the Micrographic Surgery and    Dermatologic Oncology Fellowship Mayo Clinic Rochester, Minnesota, USA

Thomas E. Rohrer, MD Dermatologic Surgeon SkinCare Physicians Chestnut Hill, Massachusetts, USA

Thuzar Shin, MD, FAAD, FACMS Hospital of the University of Pennsylvania Philadelphia, Pennsylvania, USA

Joseph F. Sobanko, MD Mohs Surgery & Reconstruction Laser Surgery & Cosmetic Dermatology Director of Dermatologic Surgery Education Associate Professor, Dermatology Hospital of the University of Pennsylvania Perelman Center for Advanced Medicine Division of Dermatologic Surgery and Cutaneous    Oncology Philadelphia, Pennsylvania, USA

Evan Stiegel, MD, FAAD, FACMS Wilson Dermatology An Affiliate of The Skin Surgery Center Wilson, North Carolina, USA

Stanislav N. Tolkachjov, MD, FAAD, FACMS Dermatologic Surgeon and Dallas-Fort Worth Area    Director Mohs Micrographic & Reconstructive Surgery Epiphany Dermatology; Clinical Assistant Professor University of Texas Southwestern Medical Center; Clinical Associate Professor Texas A&M College of Medicine; Core Faculty Division of Dermatology Baylor University Medical Center Dallas, Texas, USA

John Zitelli, MD Adjunct Associate Professor Departments of Dermatology, Otolaryngology, and    Plastic Surgery University of Pittsburgh Medical Center Pittsburgh, Pennsylvania, USA

David Zloty, MD, FRCP Clinical Professor Faculty of Medicine Department of Dermatology and Skin Science University of British Columbia Vancouver, British Columbia, Canada

1Mohs Micrographic Surgery

Abstract

The two major goals of Mohs micrographic surgery (MMS) are to provide the highest possible cure rate for the treatment of cutaneous malignancies while also ensuring that the malignancy is removed in the most conservative or tissue-sparing manner possible. While these two tenets of this procedure seem straightforward, there is a considerable amount of attention to detail and process quality that is required to provide the service patients expect from MMS. In this chapter, we outline processes and techniques that will lead to successful, reproducible execution of the MMS.

Keywords: Mohs surgery, micrographic surgery, skin cancer treatment, tissue sparing, complete circumferential peripheral and deep margin assessment, initial Mohs stages/layers, subsequent Mohs stages/layers, process improvement

Capsule Summary and Pearls

•Mohs micrographic surgery (MMS) provides the highest cure rates in the most tissue-conserving manner for most skin cancers.

•Success of the procedure relies on proper tumor selection and careful execution of the technique.

•When excising a Mohs surgical specimen, several refinements in technique can ease tissue processing, accurate tumor mapping, and ultimately reconstruction of the resultant defect.

•Awareness of the surgical and tissue processing issues that may lead to artifacts on the tissue specimen can assist the surgeon in avoiding false positive readings.

1.1 Before the First Stage

Nicholas Golda and George Hruza

1.1.1 Tumor Selection

Mohs micrographic surgery (MMS) is best suited for the treatment of malignancies that grow in a contiguous manner, meaning that they grow in a manner where the entirety of the tumor is part of a singular mass with no part being physically separated from the primary site of growth. Properly trained providers most commonly use MMS for the treatment of all subtypes of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), but the procedure is also commonly used for nearly all cutaneous adnexal malignancies—dermatofibrosarcoma protuberans (DFSP), cutaneous leiomyosarcoma, extramammary Paget’s disease (EMPD), atypical fibroxanthoma (AFX), melanoma in situ (MMIS), and, in some cases, for invasive melanoma, Merkel cell carcinoma (MCC), and other far less common cutaneous malignancies.1 The unifying feature of all malignancies treated successfully with MMS is that these tumors are contiguous, thereby allowing the surgeon to detect the totality of the microscopic, often subclinical, extent of the tumor while properly carrying out the procedure.1

Selection of the most appropriate treatment is very important for producing the best results for the patient. While MMS may be utilized for nearly all forms of cutaneous malignancy, it is important to be discerning with respect to which malignancies are treated with the procedure as there are several other alternatives for the treatment of skin cancer beyond MMS, each with its own merits and drawbacks. MMS, while not a more aggressive or arduous procedure for the patient when compared with a standard excision, is a labor-intensive procedure for the physician and the MMS team, often consisting of several individuals in addition to the physician including nurses and histotechnicians. Acknowledging this, MMS is often reserved for malignancies with any of the following features:

•Malignancies in which there is risk of disfigurement or functional loss, such as those on the head and neck, hands, feet, and genitalia.

•Malignancies that have recurred or have been incompletely treated with other treatment modalities.

•Malignancies in immunosuppressed patients, particularly for cSCC in chronic lymphocytic leukemia (CLL) and solid organ transplant patients.

•Large malignancies in any body site.

•Malignancies in patients in whom the tumor border is poorly defined, often due to severe background actinic damage or subclinical tumor growth that may occur, for example, in infiltrating tumors.

•Malignancies exhibiting aggressive growth features clinically and histologically.

•Malignancies in sites where healing is challenging and a maximally conservative technique will reduce the burden of wound healing for the patient, such as in previously irradiated fields and on the legs in patients with peripheral vascular disease or diabetes.

In an effort to create a decision aid for determining which malignancies are appropriate for treatment with MMS, the American Academy of Dermatology convened a task force to develop MMS Appropriate Use Criteria (AUC). The AUC is a publicly available guideline intended to assist physicians with medical decision-making. As a decision aid, it is not intended to replace the judgment of a treating physician in consultation with their patients. Further, it is not intended to establish a standard of care for the treatment of skin cancer as not all tumors deemed appropriate by this system must be treated with MMS, and, conversely, there are situations where the system may deem MMS inappropriate for a particular tumor, while the treating physician, taking into account additional clinical information not accounted for in the AUC, may make the decision to treat with MMS. It should also be noted that the AUC criteria are in constant evolution and are influenced not only by considerations of what is best for the patient but also by economic forces in the health care system at large.

When selecting the most appropriate treatment for skin cancer, it is important to also recognize that a skin biopsy, particularly because of its superficial nature, can misrepresent the true nature of a skin cancer. It has been shown that while carrying out definitive treatment for skin cancer, the skin biopsy underrepresented the aggressive nature of a skin cancer in up to 33% of cases, while tumors were revealed to be less aggressive than the biopsy in 17% of cases.2 Further, tumors that are not amenable to completion of treatment under local anesthesia will be challenging to complete in the outpatient setting with MMS, but MMS can be used in many of these cases as a component of multidisciplinary care for particularly advanced skin cancers such as those invading bone, foramina of the skull, or the orbit. Therefore, the clinician’s judgment, taking into sum all patient factors including clinical and possible radiologic examination, pathologic correlation with that examination, and a discussion with the patient about their goals for treatment, is still the best tool for selecting a plan for skin cancer management.

1.1.2 Documentation of Site

Cure rates are higher when the procedure is done in the correct location. It seems obvious, but in patients with small lesions or significant background actinic damage, or when anatomically inaccurate verbiage is used to describe the original biopsy site, it can, at times, be difficult to identify the correct site for surgery. Further, patients are often unable to accurately recall the correct site of a biopsy, with one study showing the rate of misidentification of the biopsy site by patients at 16.6%.3 It is therefore important to have a clearly defined process for identifying the correct site for surgery. Utilizing photography from the time of biopsy is a best practice for avoiding wrong site surgery.3 Photographs at the time of a skin biopsy should have the planned biopsy site clearly marked and should be taken from far enough away to include anatomic landmarks that can facilitate localizing the site when surgery is eventually carried out. One HIPAA (Health Insurance Portability and Accountability Act of 1996) compliant and relatively simple way to accomplish biopsy site photography is to take a picture of the marked biopsy site with the patient’s mobile phone and ask them to bring their phone with them to their surgical visit if the biopsy reveals a malignancy requiring further treatment.4,​5

In addition to utilizing photography, or when no photograph of the biopsy site is available, providers can use their clinical judgment to identify the biopsy site with confirmation by the patient using a mirror or a photograph on a tablet. Family who are present with the patient, particularly those who have assisted the patient with wound care for the biopsy site, can also be a resource for confirming the correct location for surgery.

If the correct site cannot be confirmed, the surgeon is left with a few options. First, the procedure can be cancelled with the patient returning to the referring provider for site confirmation or monitoring. Alternatively, a frozen section biopsy can be obtained from the most likely candidate location with definitive treatment being done on the same day if the biopsy confirms a skin malignancy. A frozen section biopsy can be carried out by obtaining a biopsy by any technique the surgeon feels will not adversely affect the subsequent definitive procedure if the biopsy is positive and will yield a cosmetically appropriate wound if the site is found to be free of cancer. The biopsy specimen is then processed by vertical sectioning (rather than the tangential sectioning typical of MMS) through the center of the biopsy specimen, stained, and interpreted to confirm the presence or absence of malignancy.6

Occasionally, there is an obvious biopsy site or obvious residual tumor with adjacent skin that is clinically suspicious for being involved by skin cancer but not definitely involved. In these cases, we have developed the practice of outlining the definite tumor or biopsy site with a solid line and outlining the area that is suspicious, but not certainly involved, with a dotted line. When confirming the site with the patient, we will explain that we will only start with the area marked with the solid line, but that we are suspicious that their cancer may be larger in the area of the dotted line. This helps manage our patients’ expectations by letting them know that we are doing everything we can to be conservative, but that their cancer may be larger than they thought previously (Fig. 1.1).

Fig. 1.1 Initial marking of a tumor showing the area that is certainly involved with a solid line and the area that is suspicious for involvement with a dotted line. Illustrating where you are concerned the tumor may extent prior to starting surgery can help patients prepare mentally for a defect that is larger than they may anticipate.

Once the correct surgical site has been marked and confirmed, photography and clinical examination can be used to document the site that will be operated upon as well as the native presurgical state of the patient’s anatomy. Photographic documentation and discussion of the patient’s presurgical state can assist with eventual reconstruction planning as well as protect the treating physician from being implicated as the cause of any asymmetries, deformities, or palsies that the patient has prior to the planned surgical procedure. Additionally, during this time, it can also be helpful to mark relevant anatomic boundaries prior to the instillation of anesthesia if these boundaries will be helpful during reconstruction planning. A common example where this is helpful is marking the white roll of the lip as the edema from surgery and injected anesthesia can make this landmark more challenging to visualize reliably, especially in older patients with a less well-defined vermilion border (Fig. 1.2a, b).

Fig. 1.2(a,b) Marking anatomic boundaries preoperatively can be helpful in identifying these boundaries following MMS during reconstruction planning. These boundaries are often distorted by edema following tumor removal.

1.1.3 Time-Out

A critical practice for the safe and accurate execution of a surgical procedure is the surgical “time-out.” This can be carried out in a number of ways, but essentially, the physician who will be doing the procedure must confirm that the correct procedure is being done on the correct site for the correct patient. Many Mohs surgeons do formal time-outs at the outset of the MMS and less formal time-outs with subsequent stages. The time-out for a subsequent stage can be particularly important if patients are being moved to different rooms throughout the day to ensure that the correct Mohs map is being referenced and the correct instruments are being used.

1.2 Procedures before the First Stage

Nicholas Golda and George Hruza

1.2.1 Curettage

Curettage is a common procedure in dermatology often used as a definitive treatment for superficial skin cancers in noncosmetically sensitive areas. At the outset of MMS, curettage is done to grossly define the breadth and depth of the skin cancer, but the procedure is carried out differently from curettage done in the course of malignant destruction. Prior to MMS, curettage is carried out more gently in a manner to avoid unnecessarily disrupting the surrounding epidermis in skin that is clinically uninvolved by skin cancer. This is often accomplished with reusable dermal curettes, which are typically less sharp and therefore more specific for tumor than single-use disposable curettes, which tend to be overly sharp for this purpose. Generally, working from the center of a lesion out to the periphery, the tumor shells out relatively easily providing firmer tactile feedback to the surgeon when normal dermis is encountered both peripherally and at the deep margin. Once this rigid feedback is encountered at all margins, and no soft skin cancer remains to be removed, curettage is stopped and the operative site is cleansed with gauze to remove any fragments of skin cancer that may have been freed by curettage but remain on or near the surgical site. This gauze is then discarded in order to avoid reintroducing these fragments of skin cancer to the operative field and increasing the risk of a false-positive histologic margin due to a displaced tumor fragment (▶Video 1.1).

There are several benefits to curettage prior to the first layer of MMS:

•Site confirmation as tumor in a correctly identified surgical site will typically readily curette away.

•Removal of the bulk of the malignancy gives the surgeon a better concept of the gross breadth and depth of the tumor.7 Curettage can confirm the surgeon’s clinical impression of the size of a malignancy, but it can also inform the surgeon that the malignancy is either larger or smaller than originally thought, thereby sparing the patient unnecessary subsequent layers or allowing for a more conservative procedure, respectively.

•“Floaters” and other artifactual tumor on the Mohs margins can be reduced by curettage. By removing the gross tumor, tumor fragments are less likely to be displaced into the peripheral or deep margin during tissue processing, thereby reducing the chance of false-positive tumor at the margin and making histologic interpretation less challenging.

–False-positive tumor displacement into the deep margins during relaxing cuts or specimen division is referred to as a “push-through” error (Fig. 1.3a).

–Residual tumor in the center of the specimen that hinges into the deep margin following specimen division thereby causing a false positive on the deep margin is referred to as a “fall over” error (Fig. 1.3b).

•Tissue relaxing for the purposes of tissue processing is facilitated by removal of the central bulk of the tumor by curettage.

Fig. 1.3(a,b) Curettage can assist in reducing the risk of histologic errors later in the procedure, particularly push-through artifact where gross tumor is pushed into the deep margin during processing and fall over artifact where gross tumor falls into the deep margin from the center of the tumor in divided specimens.

There are also pitfalls to the curettage process:

•Fibrous, infiltrative, incompletely excised, and recurrent malignancies will not curette well, so curettage is unreliable in these settings for defining the gross extent of the tumor.

•Curettage in areas where skin is particularly weak or thin and prone to tearing, such as an aged eyelid affected significantly by solar elastosis, may inadvertently remove normal, uninvolved tissue and introduce skin tears that can make tissue orientation and subsequent reconstruction more challenging.

•If care is not taken with the procedure or if overly sharp disposable curettes are used, then the process of curettage may damage surrounding uninvolved epidermis and make the Mohs excision larger than necessary to achieve a cure.

1.2.2 Sharp Debulking

The intent of sharp debulking of a tumor prior to excision can be manifold. The most typical use of sharp debulking is to remove the gross bulk of an exophytic tumor, thereby facilitating subsequent curettage and/or tissue processing. The surgeon may also want to obtain the center section of a tumor for histologic analysis, so this can be compared with the margins while attempting to clear the tumor. This technique can be particularly helpful for less common malignancies or malignancies where the histology is atypical or somehow in question (a “know your enemy” biopsy). Analysis of the center of a tumor may also be helpful for identifying high-risk features of the malignancy that may not have been evident on the initial diagnostic biopsy and may not be manifest on the margins of the Mohs specimens. This additional information may assist with obtaining more complete tumor staging, such as in cases of cSCC, and may provide important information for future management of the patient. Processing of the debulking specimen can either be done with horizontal frozen section processing and interpretation by the Mohs surgeon or by submitting the specimen for frozen or permanent section analysis by a dermatopathologist. In either case, a pathology report should be produced to document the findings of such biopsies.

The benefits of sharp debulking prior to the first layer of MMS are similar to those seen with curettage. Namely, removing the tumor bulk will reduce the chance of malignant tissue becoming dislodged from the tumor mass during excision and tissue processing and ending up on the examined histologic margins of the MMS specimen. When tumor cells become dislodged in this manner, it can increase false-positive interpretations or make histologic interpretation more challenging as the surgeon works to determine if the tumor is at the margin. Typically the deep margin in these cases, where specimen division or relaxing cuts push malignant tissue into the margin, is a true or false positive.

The primary pitfall of taking a debulking specimen is that the surgeon is at risk for inadvertently taking too wide or too deep a debulk, thereby making the final Mohs excision larger than necessary. This risk can be minimized through careful technique (▶Video 1.2).

1.3 The First Stage

Nicholas Golda and George Hruza

1.3.1 Essentials of the First Stage

Recall that the two principal goals of MMS are oncologic cure and maximal tissue conservation, in that order. With that said, the goal with each stage of MMS should be to conservatively remove the malignancy in its entirety. Clinical examination by the Mohs surgeon to identify the clinically obvious extent of the tumor is the best tool for determining the size of the first stage. This examination can be augmented as previously discussed by the use of curettage prior to the first stage. It is important to reiterate that while the surgeon may have suspicion that the tumor may be larger than it appears, only the clinically obvious extent of the tumor should be removed with the first stage with the surgeon using histology of the MMS margins to either confirm or refute the initial clinical suspicion. Using this technique may result in an additional stage being necessary, but it also allows for maximal tissue conservation.

The first stage consists of complete removal of the entire gross tumor as well as a 1- to 2-mm margin of clinically normal skin immediately around and deep to the tumor (▶Video 1.3). For very large or aggressive tumors, a larger initial margin may be useful to reduce the number of stages needed for tumor clearance. This rim of clinically normal tissue is needed to prove negative margins as well as to allow for monitoring of tissue processing quality by the surgeon, as will be discussed later. If care is taken while excising Mohs stages to make the tissue specimen easier for the surgeon or the histotechnician to process, the histologic section will be processed faster, and will be of higher quality and easier to interpret. Following is an outline of the first stage with suggestions for facilitating tissue processing and optimizing quality.

The first stage begins with a very superficial incision or score around the tumor at a 90-degree angle relative to the skin surface. This incision defines the margin of the specimen that will be processed. To aid in subsequent tissue processing, the border of the Mohs layer should consist of smooth, rounded, convex contours. Sharp corners, concave shapes, and start-stop chatter (rifling layers) are more challenging to relax and flatten into the proper plane for tissue processing. These imperfections in the Mohs excision can create areas where the epidermis is missing, thus making that section of the specimen uninterpretable and necessitating additional stages of surgery that may have been avoidable. Further, start-stop chatter can also cause the introduction of false tissue scores that can make tumor localization challenging (Fig. 1.4).

Fig. 1.4 A proper first stage of the MMS consists of a smooth incision immediately around the gross tumor with convex edges and inwardly beveled walls to facilitate tissue processing. Sharp corners, concave shapes, and start-stop chatter are to be avoided.

The initial incision for the Mohs excision is made superficially because the goal is to leave the specimen in perfect orientation relative to the site on the patient where it is being removed so tissue orienting marks can be precisely placed on the specimen and patient. These orienting marks can be made by different techniques and in different patterns based on surgeon preference and tumor size and shape (Fig. 1.5). The key when placing orienting marks is to ensure that, if tumor is present, the surgeon will be able to precisely localize the residual tumor on the patient based on these marks. Therefore, the marks are placed prior to incising through the full thickness of the dermis in order to ensure that the mark on the specimen side corresponds exactly to the mark on the patient side. Orienting marks are most commonly made by making a shallow nick with the scalpel in the tissue. This nick should be deep and large enough to be readily found if a subsequent stage is required, but not so large and deep as to interfere with reconstruction. The pattern of tissue nicks is highly variable among surgeons. The surgeon must select the technique they feel will allow them the greatest ability to locate and selectively excise residual tumor using histologic maps. One key is that, regardless of what technique is used, the orienting marks should be asymmetric. By making the marks asymmetric, the surgeon can reorient the specimen to the patient if any tissue handling error occurs during tissue processing, such as a dropped specimen or a mislabeled map, because the specimen will only “fit” on the patient’s defect one way much like an asymmetric shaped peg will only fit into its corresponding hole in the correct orientation.

Fig. 1.5 Common patterns for placing tissue orientation marks.

Surgeons use several techniques to make orienting marks. Some use gentian violet in order to avoid tissue scores, but gentian violet has a tendency to lose its sharpness on the skin (“bleed”) and can be washed away by surgical preps and blood between stages, thus negatively affecting precision of tumor location. More commonly, surgeons use orienting nicks in the tissue as discussed earlier. Common asymmetric patterns include a single score in one location and three scores in a 12, 3, and 6 o’clock position or similar asymmetric orientation. Alternatively, many providers will place four scores in a symmetric crosshairs orientation, though this does require more care to maintain orientation as the symmetry of the scores does not allow reorientation if there is a tissue handling error during tissue transfer, grossing, or processing. When tissue nicks are placed, it is helpful to place them in line with the most likely vector of closure, so the nicks will be excised with standing cones and not confound epidermal approximation during wound closure. Larger tumors are best scored with a “gridding” technique that allows the highest possible resolution for residual tumor in the deep margin within the larger field of these tumors. In this technique, scores are placed such that the tissue can be divided into graph paper–like squares during tissue processing. Another method of marking very large tumors is the use of skin staples around the defect margins matching staples in the specimen excised. Staples can also be useful for orienting deep margin tumor resection without a skin edge with the staples used to outline the margins of the specimen excised (Fig. 1.6).

Fig. 1.6 Large tumors, such as the dermatofibrosarcoma protuberans pictured, are best oriented with marks placed in a grid pattern so residual tumor at deep margins can be easily resolved and accurately removed. Large tumors such as these are best marked redundantly with gentian violet and tissue scores.

When placing scores, the surgeon must balance resolution of tumor location during tissue analysis with the fallibility introduced by placing several orienting scores in the specimen. The ability of the surgeon to precisely identify, on the patient, where residual tumor remains for selective re-excision in a subsequent stage is improved if the tumor is near an orienting score. Therefore, the more scores a surgeon places in the specimen, the greater their ability to precisely locate the residual tumor on the patient. Scores, however, introduce potential error into the MMS because each score produces an area where epidermis may be incompletely laid down into the sectioning plane. If the score results in failure to visualize focal residual tumor on a margin because of incomplete epidermal lay-down, then cure rates can be negatively affected. The decision for how many scores are necessary to accomplish the goals of MMS is therefore left to the surgeon to determine based on confidence in individual practice laboratory techniques and ability to localize tumor within a specimen with more or less scores.

Next, a beveled incision is used to incise into the skin, and into deeper tissues, if necessary, to the desired depth of the excision below the grossly evident depth of the malignancy. This beveled incision is accomplished by taking several passes around the specimen within the superficial initial incision, at approximately a 45-degree angle in most cases, until the correct depth is reached. Excising the tissue with a bevel eases the process of laying the epidermal edge flat into the same plane as the deep margin during tissue processing as the epidermal edge travels a smaller distance and encounters less torsional resistance when the tissue is beveled relative to a 90-degree excision (Fig. 1.7). The amount of bevel needed varies based on the anatomic site of the tumor (as the dermis is more or less rigid in different sites) and the depth of the tumor (shallow, dermis-only layers need a greater degree of beveling as do tumors that are deeper than they are wide).8 It is common, for example, on distal nasal and nasal alar lesions to take a transdermal layer in an effort to facilitate a better outcome with a skin graft or second intention healing, but such transdermal layers typically need more extreme beveling in order to facilitate high-quality tissue processing due to the stiffness of the dermis (▶Video 1.4). This has been referred to as the partial-thickness layer technique.8,​9

Fig. 1.7 Demonstration of appropriate bevels. Having too little bevel can cause difficulty with tissue processing, while too much bevel may inadvertently transect the tumor within the wall of the specimen.

Finally, once the beveled incision at the periphery of the specimen is complete, the specimen is removed from the patient by making a flat incision across the deep margin of the specimen at a depth just below the deepest extent of the tumor. In some cases, this depth may be intradermal. In others, it may be deeper at any level down to and including periosteum. Errors that can be made during incision of the deep margin include the following (Fig. 1.8a–e):

Fig. 1.8 Pitfalls with the deep margin on an initial Mohs stage. (a) A jagged deep margin. (b) Drifting superficially or deep within the deep plane. (c) Antibeveled deep margin. (d) A buttonholed deep margin. (e) Grasping the deep margin too firmly with toothed forceps producing a hole in the deep margin.

•Making an incision that is not flat: A jagged deep marginal incision will increase the likelihood of dropout areas, leading to the possibility of false negatives.

•Making an incision that drifts more superficially or more deeply across the deep margin:

–Shallow drift: Risks more stages by inadvertently incising into the deep margin of the tumor.

–Deep drift: Unnecessary tissue waste, volume loss, and possible damage to deeper structures such as nerves or vessels.

•Creating an antibevel that interferes with tissue relaxing by incising the entirety of a deep margin across the specimen from one direction.

•Incomplete or buttonholed deep margin:

–Creates an area of uninterpretable deep margin “dropout” by incising into the curetted deep margin of the specimen or creating extra notches mimicking those planned for orientation.

•Grasping the tissue too firmly with toothed forceps while removing the specimen can create triangular impressions in the deep margin that impair assessment of the complete deep margin:

–Toothed forceps may also transfer malignant tissue from the tumor to the deep margin if care is not used to only use one side of the forceps on the tumor side and the other on the deep side while grasping the tissue.

1.3.2 Incomplete Excision and Recurrence

The process of taking a first Mohs stage from a site that has been previously excised or is recurrent following a prior excisional procedure presents unique challenges. An incompletely excised tumor is one where an excision has been attempted and the pathology revealed persistent malignancy at a lateral or deep margin. Having information about whether the residual tumor is present at lateral or deep margins, or having the slides from the original excisional specimen available for review, can be helpful when planning subsequent MMS. The issue created by an incompletely excised or recurrent tumor is that the malignancy may no longer be contiguous and/or may be obscured by scar clinically and histologically. This is why cure rates for MMS are highest when MMS is the first treatment selected for a tumor.10,​11 In our practice, we will typically execute a “mapping layer” in the cases of incomplete excision as the first stage of MMS (Fig. 1.9). A mapping layer essentially consists of a narrow re- excision of the entirety of the scar from the prior procedure to include tissue below the deep margin of the prior procedure. This complete re-excision of the deep margin below the prior scar is essential to prove negative deep margins with MMS. The deep margin of a prior excision can be identified both clinically and histologically by visualizing scar rather than normal subcutaneous fat on the deep margin. In cases of recurrence and incomplete excision, it is only possible to prove clear margins by complete histologic assessment of the prior surgical margins. This requires careful re-excision of the prior procedure and understandably causes additional tissue loss and occasionally large defects that may have been avoided if MMS was used for primary treatment of the malignancy.

Fig. 1.9 Mohs mapping for a previously excised tumor (Mohs for a prior incomplete excision).

1.4 Tissue Processing

Nicholas Golda and George Hruza

1.4.1 Tissue Transfer

Once the MMS specimen has been excised, it is placed on a transfer medium for transport to the grossing table. The medium used is variable among Mohs practices and may consist of cardstock or paper with or without anatomic drawings drawn or preprinted, filter paper, nonadherent pads, or saline-soaked gauze. Further, some practices use Petri dishes to house tissue and the aforementioned transfer medium to transport tissue to the laboratory for processing. Regardless of the transfer medium selected by an individual surgeon, some things are consistent between practices:

•Most media have a mechanism for identifying the location of orienting marks, or at least the 12 o’clock position, on the excised tissue. This can be accomplished with detailed drawn maps on preprinted cards or a simple ink mark on a nonadherent pad or gauze (Fig. 1.10).

•There must be a mechanism for identifying the patient and site or accession number to avoid confusing specimens with one another in the lab (Fig. 1.10).

•