Large acquired nevocytic nevi induced by the Koebner phenomenon.

A patient with characteristic clinical, histopathological, ultrastructural and family history of epidermolysis bullosa simplex (EBS) developed large acquired nevocytic nevi at the sites of some healing blisters. An isomorphic reaction may have initiated the development of these nevi. Such large acquired nevi should be considered in the differential diagnosis of large and giant congenital nevi which have the potential to evolve into malignant melanoma.