Pathology quiz. A pigmented skin lesion

Melanomas can usually be distinguished histologically from benign lesions by the application of accepted criteria of high discriminatory value. Occasionally, the distinction cannot be made with certainty. It is convenient to consider cutaneous melanoma as essentially of one type, with the prognosis being mainly determined by the thickness of the lesion. There is a trend to narrower excision margins with adequacy being judged solely by careful histological assessment. A formula-driven approach should be avoided.