Melanoma In Situ Margins — SCE Dermatology MCQ

Correct answer: D — 5 mm clinical margin

BAD guidelines recommend a 5 mm clinical excision margin for melanoma in situ. For lentigo maligna type melanoma in situ on the face (where tissue conservation is critical), staged excision with mapped margin control using permanent sections is preferred because subclinical extension is common — the clinical margin of 5 mm may be insufficient in 10-20% of cases. Standard Mohs with frozen sections is NOT recommended for melanoma in situ because melanocyte atypia is difficult to assess reliably on frozen section. Slow Mohs with paraffin sections and immunohistochemistry (Melan-A/MART-1) is the gold standard for facial lentigo maligna.

Reference: BAD 2017 Melanoma Excision Margins