Case 32 Female, 31 years, pregnant. Skin papule, buttock, has grown and darkened.Show diagnosis & comments
Predominantly intradermal naevus
There is some mitotic activity and hyperpigmentation, presumably related to pregnancy. Junctional melanocytes are large; this has been called ‘atypical junctional melanocytic proliferation’. This feature is of no concern and should not be diagnosed as in situ melanoma, or raise a suspicion of in situ melanoma.
Okamura JM, Barr RJ, Cantos KA. Benign atypical junctional melanocytic hyperplasia associated with intradermal nevi: a common finding that may be confused with melanoma in situ. Mod Pathol. 2000 Aug;13(8):857-60.