This is a malignant melanoma, showing ulceration and variation in pigmentation. The surgeon has performed a wide excision, taking a wider margin in the line of lymphatic drainage. Originally a
5cm margin was recommended but recent work suggests that small lesions up to 2mm require only a 1cm margin and larger lesions require a 2cm margin. The Breslow depth is used as a prognostic indicator with "thin" melanomas being less that 1mm in thickness, "intermediate" being 1-4mm and "thick" being greater than 4mm. Clark's levels are more subjective.