2. Mohs micrographic surgery SWAG network service Update May 2016
Dr Adam Bray
Consultant Dermatologist
Dermatological & Mohs surgeon
Bristol

3. Bristol Mohs service Since Feb 2015
Approximate waiting list 3 months once seen (less for eyelids)
Second Mohs surgeon Dr Pawel Bogucki
Excellent links with local Plastic surgery, Oculoplastics, and Maxillofacial 
Southmead Hospital, North Bristol NHS Trust (NBT)
Any interested clinicians are welcome to arrange a visit for their professional development

4. Referrals Please write to me stating:
‘Referral for Mohs surgery, Dermatology department’:
Southmead Hospital, North Bristol Trust

5. Bristol Mohs service 110 cases treated (now usually 4 per week)
Mainly Bristol
Also Bath, Swindon, Cheltenham & Gloucester
First 81 cases analysed
Defect size mean = 29mm
Tumour size mean = 22mm
91% reconstructed by Dermatology (rest Plastics, and Oculoplastics)
Almost all on the same day
3 all day GA combined cases (Plastics, Oculoplastics, Mohs)
Combined Oculoplastic list for eyelid cases every 1-2 months

6. What needs Mohs?
Tumours that can be easily excised with a sufficiently wide margin to guarantee cure without significantly affecting the repair do not need Mohs.
A 'rule of thumb' is as follows:
- Can I confidently excise the tumour with the recommended clinical margin & repair optimally?
- If not, Mohs (or other margin controlled surgery) should be considered

7. On the SWAG website

8. Possible Indications for Mohs (in order of strength)
Poorly defined borders
Anatomical location:
‘H-zone’ (high risk of recurrence)
Sites where sparing tissue highly important
Recurrent
Incompletely excised
Infiltrative/Morphoeic
Large (>2cm)
Immunosuppressed/Gorlin syndrome
N.B. Mohs is usually used for head and neck BCC, but other sites and tumours can be considered.
N.B. Strongly consider Mohs for recurrent or incompletely excised tumours, unless straightforward to take generous deeper layer, or skin margins of 6-10mm+ (for recurrences) or 4-6mm+ (for positive margins) as recommended for standard excision/pathology.

9. Situations where Mohs is difficult If a GA is unavoidable
If bone is involved (but Mohs can still be useful to clear skin)
Consider other margin controlled surgery e.g. ‘spaghetti technique’
The “spaghetti technique”: An alternative to Mohs surgery or staged surgery for problematic lentiginous melanoma (lentigo maligna and acral lentiginous melanoma).
J Am Acad Dermatol. Elsevier Inc; 2011 Jan 1;64(1):113–8.

10. Summary of Key Mohs Benefits
Maximum cure rate
Healthy tissue sparing potential
Fast results

11. What needs Mohs? Avoid intra-operative frozen section analysis
Consider Mohs over delayed repair
Why? The pathology is FAR more accurate
Avoid intra-operative frozen section analysis
Why? Shown to be VERY inaccurate

12. False-negative rate of intraoperative frozen section margin analysis for complex head and neck nonmelanoma skin cancer excisions
M. D. Moncrieff, A. K. Shah, L. Igali, J. J. Garioch
Volume 40, Issue 8, pages 834–838, December 2015

13. A. Because they were not fully removed
Mohs Micrographic Surgery
Q. Why are tumours incompletely excised? A.
-Because they are difficult to see
-Because they grow unpredictably
Q. Why do tumours recur?
A. Because they were not fully removed

14. Mohs: Horizontal Sections
Mohs Micrographic Surgery
Mohs: Horizontal Sections

15. RCT: Smeets et al; Lancet 2008
Mohs Micrographic Surgery
RCT: Smeets et al; Lancet 2008
Cure Rates
Optimal Standard Excision +- Mohs
Mohs Micrographic Surgery
Comment
Primary BCC
96%
98%
1. Not just high risk BCC (e.g. 1cm nod nose).
2. 30% lost to FU.
3. More complex tumours in Mohs group.
4. ‘Standard’ Group not standard.
5. All incompletely excised tumours had re-excision or Mohs.
Recurrent BCC
88%
5 year follow-up

16. 2 Large Prospective Case Series
Mohs Micrographic Surgery
2 Large Prospective Case Series
Malhotra R et al. The Australian Mohs database, part II: periocular basal cell carcinoma outcome at 5-year follow-up. Ophthalmology 2004; 111:631–6.
Periocular 819 patients
Cure rates: Primary 100%; Recurrent 92%
Leibovitch I et al. Basal cell carcinoma treated with Mohs surgery in Australia II. Outcome at 5-year follow-up. J Am Acad Dermatol 2005; 53:452–7.
3370 patients
Cure rates: Primary 98.6%; Recurrent 96%

18. Discharge to GP or referrer
Referral ?BCC
Curettage & electrodessication or Cryotherapy (usually in clinic)
Clinic FU
Clinic or phone FU or letter
Derm/plastics appt
Diagnostic biopsy
Discharge to GP
Topical treatment
Excision
Clinic FU
Clinic or phone FU or letter
ECT
Clinic or phone FU or letter
Radiotherapy
Discharge to GP
MDT meeting
Discharge to GP or referrer
Radiotherapy assessment FU
Mohs surgery FU
Mohs assessment clinic or phone FU or letter
Discharge to GP or referrer

19. BSDS UK Mohs Standards 2012 New (first) UK quality standards document
Mohs Micrographic Surgery
BSDS UK Mohs Standards 2012
New (first) UK quality standards document
Training standards
Usually a 1 year post-CCT advanced skin cancer surgery fellowship
100 varied cases
Participation in further 250 cases
Curriculum being ratified by SAC/RCP/GMC
Workload
cases per Mohs surgeon per year
400 cases per training unit

20. Thanks for listening

21. Referrals Please write to me stating:
‘Referral for Mohs surgery, Dermatology department’:
Southmead Hospital, North Bristol Trust

22. What needs Mohs?
Tumours that can be easily excised with a sufficiently wide margin to guarantee cure without significantly affecting the repair do not need Mohs.
A 'rule of thumb' is as follows:
- Can I confidently excise the tumour with the recommended clinical margin & repair optimally?
- If not, Mohs (or other margin controlled surgery) should be considered

23. End

24. The Mohs procedure explained

25. Pathology – nodular BCC
Mohs Micrographic Surgery
Pathology – nodular BCC

26. Pathology – Micronodular BCC
Mohs Micrographic Surgery
Pathology – Micronodular BCC

27. Pathology – Infiltrative BCC
Mohs Micrographic Surgery
Pathology – Infiltrative BCC

28. BCC Spread Beyond Clinical Margins
Mohs Micrographic Surgery
BCC Spread Beyond Clinical Margins
BCC Type
Clinical Excision Margin Around Tumour
Complete Clearance Rate (not cure)
<20mm & Well-defined
3mm
85%
4mm - 5mm
95%
Morphoeic
66%
5mm
82%
13mm – 15mm
>95%
Determined by Mohs pathology.
Breuninger H, Dietz K. Prediction of subclinical tumor infiltration in basal cell carcinoma. J Dermatol Surg Oncol 1991; 17:574–8.
Kimyai-Asadi A, Goldberg LH, Peterson SR et al. Efficacy of nar- row-margin excision of well-demarcated primary facial basal cell carcinomas. J Am Acad Dermatol 2005; 53:464–8.
Telfer N, Colver G, Morton C. Guidelines for the management of basal cell carcinoma. Br J Dermatol Jul. 1;159(1):35–48.

29. Standard Pathology Standard protocol Usually 4-6 x3mm slices
5 micron shaves from each slice
Usually <5% of margins seen
Standard Pathology

30. Standard Tumour Pathology - NBT
Mohs Micrographic Surgery
Standard Tumour Pathology - NBT
Bread-loafing
3mm slices
Shaves taken from each
Tips separate: shaved off broad end
If tumour found, tips rotated and shaves taken from sharp end
Saves going through whole specimen
No standardisation

31. Mohs Micrographic Surgery
Standard Pathology

32. The Mohs Excision – Cross Section
Mohs Micrographic Surgery
The Mohs Excision – Cross Section
PRESSURE DOWNWARDS
SQUASHED FLAT
UNDERSIDE OF SPECIMEN
100% OF MARGINS ON 1 PLANE
Superficial Peripheral Margin
Deep Margin
Deep Peripheral Margin

33. Mohs: Flattening the specimen
Mohs Micrographic Surgery
Mohs: Flattening the specimen