A prospective two-month epidemiologic and histologic study of all mela
nocytic nevi biopsied (n = 434) at the University of Okla homa Health
Center was undertaken. Melanocytic nevi with papillomatous features (P
AP) (n=50) were found to occur predominantly in females (females = 44,
males = 6; p < 0.01 adjusted for sex distribution of all melanocytic
nevi). Immunohistochemical analysis of melanocytic nevi revealed conco
rdance between PAP and intracytoplasmic nevocellular staining for estr
ogen-inducible pS2 protein. Melanocytic nevi without papillomatous fea
tures failed to stain for pS2 protein. These results suggest a hormone
responsiveness exclusive of patient sex which may influence the patho
genesis of these distinctive melanocytic nevi.