Case 2 Male, 42 years. Irregular skin papule, back.Show diagnosis & comments
Superficial spreading melanoma with naevus remnant.
This melanoma shows the phenomenon of 'epidermal consumption': flattening and thinning of the overlying epidermis, with diminuition of the number of cell laters. This may result from the massive accumulation of underlying melanoma cellls which stretches the overlying epidermis, and possibly associated ischaemia. It is likely that progression of this process will result in ulceration of the melanoma.
At the base of the melanoma, there are small groups of naevus cells (contrasting with the much larger melanoma cells immediately above them), probably the remnant of a naevus from which is melanoma has arisen.
Hantschke M, Bastian BC, LeBoit PE. Consumption of the epidermis: a diagnostic criterion for the differential diagnosis of melanoma and Spitz nevus. Am J Surg Pathol. 2004 Dec;28(12):1621-5.