Keratinocyte cancer

7.8 Criteria for choosing Mohs micrographic surgery in preference to other surgical techniques

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Clinical practice guidelines for keratinocyte cancer > 7.8 Criteria for choosing Mohs micrographic surgery in preference to other surgical techniques

Background[edit source]

Mohs micrographic surgery (MMS) is named after Frederick Mohs, who pioneered this technique. His original chemosurgery procedure has been modified to a fresh frozen tissue technique.

In Australia the Australian College of Dermatologists (ACD) maintains the register of physicians who can claim the Mohs Medicare item number. The ACD is responsible for training, accreditation and ongoing professional requirements to remain on the Mohs register. The ACD also sets Appropriate Use Criteria for the Mohs surgery and Clinical Benchmarks, which have been adopted by Medicare. It is undertaken in several specialised centres in Australia[1][2][3][4][5][6][2][7] and is primarily used in a tertiary referral setting for difficult-to-treat tumours.

Mohs surgery is usually performed under local anaesthetic. Following excision of the tumour, almost the entire peripheral and deep margins of the excised tissue are examined by frozen section (see Figure 1).[8][9][10][11][12][13][14] In contrast, standard sectioning used by pathologists may examine only 0.1–1.0% of the surgical margin.

Figure 1. A, Mohs micrographic surgery technique. B, Standard technique for wide local excision with breadloaf histology. Reprinted from Mayo Clinic Proceedings, Vol. 92, Tolkachjov SN, Brodland DG, Coldiron BM et al, Understanding Mohs micrographic surgery: a review and practical guide for the nondermatologist, pp. 1261‐1271, Copyright 2017, with permission from Elsevier

The MMS technique, through a combination of specialised tissue processing and mapping ,allows precise localisation of residual tumour. It aims to ensure complete tumour clearance while maximising normal tissue conservation and function.[15][16][17][18][19][20][21][22][23][24][25][26][27][28][10][29][30] The technique is based on the principle of contiguous tumour growth. Previous treatment by breaking up a tumour can limit its effectiveness. Furthermore, the suitability of a tumour for frozen section analysis is an important part of case selection.[14]

An advantage of MMS is that the proceduralist removing the tumour also examines the histological slides, thus eliminating the communication errors that can occur in a multidisciplinary approach.[31]

The procedure requires specialised equipment and staff. Each excision takes 5–30 minutes and the processing and reading of stained frozen sections takes from 15 minutes to one hour. The total procedure may take up to several hours depending on the size and complexity of the specimen. The technique requires specific training and expertise, both for the MMS proceduralist and also for the assisting technicians.

Mohs surgery is becoming increasingly available and therefore it is important that medical practitioners treating skin cancer know about it. It is a highly specialised technique required for a small number of tumours that fit specific criteria, the decision to offer MMS should be by a medical practitioner experienced in skin cancer diagnosis and management who has a clear understanding of the technique and its value.

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Overview of evidence (non-systematic literature review)[edit source]

The criteria for choosing Mohs over other techniques include scenarios where a clear advantage in tumour cure are present and/or where the tissue sparing capacity of the technique would be significant.

Cure rates[edit source]

A systematic review and meta-analysis reported a significantly reduction in 5-year recurrence rate with MMS compared with standard excision for recurrent high-risk facial basal cell carcinoma (BCC). The study was unable to make a conclusion for other types of BCC and SCC.[32]

A RCT conducted over 10 years in the Netherlands compared MMS with standard excision for primary and recurrent facial BCC. The final analysis showed a lower 10‐year recurrence rate with MMS for high risk facial BCC when compared with standard excision. However, the difference in recurrence rates was only statistically significant for recurrent tumours. A high proportion of recurrences occurred after more than 5 years’ follow-up. The study findings emphasise the long follow-up required for some facial BCCs. More research is required in this area, particularly with regard to high-risk primary facial BCCs.[33]

There are no RCTs comparing MMS and wide excision for the treatment of SCC to date. There is lower level evidence (2a and 2b) which supports the use of MMS for the treatment of SCC.[34][35][2][36][37]

When comparing MMS and wide excision for management of BCC and SCC:[34][35][2][36][37]

  • MMS achieves a superior cure rate than wide excision for high-risk recurrent BCC of the face
  • MMS and wide excision achieve similar cure rates for primary BCC of the face
  • MMS and wide excision achieve similar cure rates for the management of cSCC of the face.

Defect size[edit source]

Available data support the argument that, across a variety of clinical scenarios for BCC excision, MMS may reduce the defect area compared with wide excision.[38][39][40][41][42] Whether this is important in a clinical scenario is unknown. Smaller defects do not always lead to easier reconstruction or repair.

Practice Point[edit source]

Practice pointQuestion mark transparent.png

PP 7.8.1. Mohs micrographic surgery may also be considered as an alternative to wide surgical excision in the following types of basal cell carcinoma:

  • poorly defined clinical border
  • infiltrating, micronodular, sclerosing, and other aggressive histological subtypes
  • residual following previous treatment
  • located in the H‐zone of the face
  • large >10mm in diameter on the face
  • if utilising MMS compared to wide excision the defect size reduction would be of clinical value.
Key point(s)
  • Mohs micrographic surgery should be considered in the treatment of high risk recurrent basal cell carcinoma of the face.
  • The decision to offer Mohs micrographic surgery should be made by a medical practitioner experienced in skin cancer diagnosis and management who has a clear understanding of the technique and its value.

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References[edit source]

  1. Leibovitch I, Huilgol SC, Selva D, Richards S, Paver R. Basal cell carcinoma treated with Mohs surgery in Australia II. Outcome at 5-year follow-up. J Am Acad Dermatol 2005 Sep;53(3):452-7 Available from:
  2. 2.0 2.1 2.2 2.3 Leibovitch I, Huilgol SC, Selva D, Hill D, Richards S, Paver R. Cutaneous squamous cell carcinoma treated with Mohs micrographic surgery in Australia I. Experience over 10 years. J Am Acad Dermatol 2005 Aug;53(2):253-60 Available from:
  3. Malhotra R, Huilgol SC, Huynh NT, Selva D. The Australian Mohs database, part II: periocular basal cell carcinoma outcome at 5-year follow-up. Ophthalmology 2004 Apr;111(4):631-6 Available from:
  4. Malhotra R, Huilgol SC, Huynh NT, Selva D. The Australian Mohs database, part I: periocular basal cell carcinoma experience over 7 years. Ophthalmology 2004 Apr;111(4):624-30 Available from:
  5. Malhotra R, Huilgol SC, Huynh NT, Selva D. The Australian Mohs database: periocular squamous cell carcinoma. Ophthalmology 2004 Apr;111(4):617-23 Available from:
  6. Leibovitch I, Huilgol SC, Selva D, Richards S, Paver R. Basal cell carcinoma treated with Mohs surgery in Australia III. Perineural invasion. J Am Acad Dermatol 2005 Sep;53(3):458-63 Available from:
  7. Leibovitch I, Huilgol SC, Selva D, Richards S, Paver R. Basosquamous carcinoma: treatment with Mohs micrographic surgery. Cancer 2005 Jul 1;104(1):170-5 Available from:
  8. Epstein E. How accurate is the visual assessment of basal carcinoma margins? Br J Dermatol 1973 Jul;89(1):37-43 Available from:
  9. Burg G, Hirsch RD, Konz B, Braun-Falco O. Histographic surgery: accuracy of visual assessment of the margins of basal-cell epithelioma. J Dermatol Surg 1975 Oct;1(3):21-4 Available from:
  10. 10.0 10.1 Abide JM, Nahai F, Bennett RG. The meaning of surgical margins. Plast Reconstr Surg 1984 Mar;73(3):492-7 Available from:
  11. Silverman MK, Kopf AW, Bart RS, Grin CM, Levenstein MS. Recurrence rates of treated basal cell carcinomas. Part 3: Surgical excision. J Dermatol Surg Oncol 1992 Jun;18(6):471-6 Available from:
  12. Davidson TM, Nahum AM, Haghighi P, Astarita RW, Saltzstein SL, Seagren S. The biology of head and neck cancer. Detection and control by parallel histologic sections. Arch Otolaryngol 1984 Mar;110(3):193-6 Available from:
  13. Rapini RP. Comparison of methods for checking surgical margins. J Am Acad Dermatol 1990 Aug;23(2 Pt 1):288-94 Available from:
  14. 14.0 14.1 Rapini RP. Pitfalls of Mohs micrographic surgery. J Am Acad Dermatol 1990 Apr;22(4):681-6 Available from:
  15. Rowe DE, Carroll RJ, Day CL Jr. Long-term recurrence rates in previously untreated (primary) basal cell carcinoma: implications for patient follow-up. J Dermatol Surg Oncol 1989 Mar;15(3):315-28 Available from:
  16. Rowe DE, Carroll RJ, Day CL Jr. Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. Implications for treatment modality selection. J Am Acad Dermatol 1992 Jun;26(6):976-90 Available from:
  17. Rowe DE, Carroll RJ, Day CL Jr. Mohs surgery is the treatment of choice for recurrent (previously treated) basal cell carcinoma. J Dermatol Surg Oncol 1989 Apr;15(4):424-31 Available from:
  18. Julian CG, Bowers PW. A prospective study of Mohs' micrographic surgery in two English centres. Br J Dermatol 1997 Apr;136(4):515-8 Available from:
  19. Robins P. Chemosurgery: my 15 years of experience. J Dermatol Surg Oncol 1981 Oct;7(10):779-89 Available from:
  20. Roenigk RK, Ratz JL, Bailin PL, Wheeland RG. Trends in the presentation and treatment of basal cell carcinomas. J Dermatol Surg Oncol 1986 Aug;12(8):860-5 Available from:
  21. Smeets NW, Kuijpers DI, Nelemans P, Ostertag JU, Verhaegh ME, Krekels GA, et al. Mohs' micrographic surgery for treatment of basal cell carcinoma of the face--results of a retrospective study and review of the literature. Br J Dermatol 2004 Jul;151(1):141-7 Available from:
  22. Robins P, Rodríguez-Sains R, Rabinovitz H, Rigel D. Mohs surgery for periocular basal cell carcinomas. J Dermatol Surg Oncol 1985 Dec;11(12):1203-7 Available from:
  23. Tromovitch TA, Beirne G, Beirne C. Mohs' technique (cancer chemosurgery). Treatment of recurrent cutaneous carcinomas. Cancer 1966 Jun;19(6):867-8 Available from:
  24. Sakura CY, Calamel PM. Comparison of treatment modalities for recurrent basal cell carcinoma. Plast Reconstr Surg 1979 Apr;63(4):492-6 Available from:
  25. Mohs FE, Zitelli JA. Microscopically controlled surgery in the treatment of carcinoma of the scalp. Arch Dermatol 1981 Dec;117(12):764-9 Available from:
  26. Mohs F, Larson P, Iriondo M. Micrographic surgery for the microscopically controlled excision of carcinoma of the external ear. J Am Acad Dermatol 1988 Oct;19(4):729-37 Available from:
  27. Mohs FE. Micrographic surgery for the microscopically controlled excision of eyelid cancers. Arch Ophthalmol 1986 Jun;104(6):901-9 Available from:
  28. Wennberg AM, Larkö O, Stenquist B. Five-year results of Mohs' micrographic surgery for aggressive facial basal cell carcinoma in Sweden. Acta Derm Venereol 1999 Sep;79(5):370-2 Available from:
  29. Ampil FL, Hardin JC, Peskind SP, Stucker FJ. Perineural invasion in skin cancer of the head and neck: a review of nine cases. J Oral Maxillofac Surg 1995 Jan;53(1):34-8 Available from:
  30. Dzubow LM, Rigel DS, Robins P. Risk factors for local recurrence of primary cutaneous squamous cell carcinomas. Treatment by microscopically controlled excision. Arch Dermatol 1982 Nov;118(11):900-2 Available from:
  31. Lane JE, Kent DE. Surgical margins in the treatment of nonmelanoma skin cancer and mohs micrographic surgery. Curr Surg 2005 Sep;62(5):518-26 Available from:
  32. Foroozan M, Beauchet A, Funck-Brentano E, Sei JF, Saiag P. Current evidence on recurrence rate of basal cell and squamous cell carcinomas treated by Mohs micrographic surgery: Systematic review. J Am Acad Dermatol 2014;70(5).
  33. van Loo E, Mosterd K, Krekels GA, Roozeboom MH, Ostertag JU, Dirksen CD, et al. Surgical excision versus Mohs' micrographic surgery for basal cell carcinoma of the face: A randomised clinical trial with 10 year follow-up. Eur J Cancer 2014 Nov;50(17):3011-20 Available from:
  34. 34.0 34.1 Lansbury L, Bath-Hextall F, Perkins W, Stanton W, Leonardi-Bee J. Interventions for non-metastatic squamous cell carcinoma of the skin: systematic review and pooled analysis of observational studies. BMJ 2013 Nov 4;347:f6153 Available from:
  35. 35.0 35.1 Pugliano-Mauro M, Goldman G. Mohs surgery is effective for high-risk cutaneous squamous cell carcinoma. Dermatol Surg 2010 Oct;36(10):1544-53 Available from:
  36. 36.0 36.1 Chren MM, Linos E, Torres JS, Stuart SE, Parvataneni R, Boscardin WJ. Tumor recurrence 5 years after treatment of cutaneous basal cell carcinoma and squamous cell carcinoma. J Invest Dermatol 2013 May;133(5):1188-96 Available from:
  37. 37.0 37.1 Stuart SE, Schoen P, Jin C, Parvataneni R, Arron S, Linos E, et al. Tumor recurrence of keratinocyte carcinomas judged appropriate for Mohs micrographic surgery using Appropriate Use Criteria. J Am Acad Dermatol 2017 Jun;76(6):1131-1138.e1 Available from:
  38. Muller FM, Dawe RS, Moseley H, Fleming CJ. Randomized comparison of Mohs micrographic surgery and surgical excision for small nodular basal cell carcinoma: tissue-sparing outcome. Dermatol Surg 2009 Sep;35(9):1349-54 Available from:
  39. Smeets NW, Krekels GA, Ostertag JU, Essers BA, Dirksen CD, Nieman FH, et al. Surgical excision vs Mohs' micrographic surgery for basal-cell carcinoma of the face: randomised controlled trial. Lancet 2004 Nov;364(9447):1766-72 Available from:
  40. van Kester MS, Goeman JJ, Genders RE. Tissue-sparing properties of Mohs micrographic surgery for infiltrative basal cell carcinoma. J Am Acad Dermatol 2019 Jun;80(6):1700-1703 Available from:
  41. Gniadecki R, Glud M, Mortensen K, Bang B, Biskup E, Omland SH. Favourable results of Mohs micrographic surgery for basal cell carcinoma. Dan Med J 2015 Dec;62(12):A5171 Available from:
  42. van der Eerden PA, Prins ME, Lohuis PJ, Balm FA, Vuyk HD. Eighteen years of experience in Mohs micrographic surgery and conventional excision for nonmelanoma skin cancer treated by a single facial plastic surgeon and pathologist. Laryngoscope 2010 Dec;120(12):2378-84 Available from:

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