ORIGINAL ARTICLESDesmoplastic (Sclerotic) Nevus An Underrecognized Entity That Resembles Dermatofibroma and Desmoplastic MelanomaHarris, Geoffrey R. M.D.; Shea, Christopher R. M.D.; Horenstein, Marcelo G. M.D.; Reed, Jon A. M.D.; Burchette, James L. Jr. H.T. (A.S.C.P.); Prieto, Victor G. M.D., Ph.D. Author Information From the Departments of Pathology (G.R.H., C.R.S., M.G.H., J.L.B., V.G.P.) and Dermatology (C.R.S., V.G.P.), Duke University Medical Center, Durham, North Carolina; and the Departments of Pathology and Dermatology (J.A.R.), The New York Hospital-Cornell Medical Center, New York, New York, U.S.A. Address correspondence and reprint requests to Dr. Victor G. Prieto, Department of Pathology, Box 3712, Duke University Medical Center, Durham, NC 27710, U.S.A. The American Journal of Surgical Pathology: July 1999 - Volume 23 - Issue 7 - p 786 Buy Abstract Desmoplastic (sclerotic) nevus, a benign melanocytic neoplasm characterized by predominantly spindle-shaped nevus cells within a fibrotic stroma, can be confused with fibrous lesions and other melanocytic proliferations, including desmoplastic melanoma. We compared the histologic and immunohistochemical features of 16 desmoplastic nevi, nine desmoplastic melanomas, four hypopigmented blue nevi, and six dermatofibromas. The similarities between desmoplastic nevi and dermatofibromas included epidermal hyperplasia (12 of 16), presence of keloidal collagen (15 of 16), hypercellularity (16 of 16), and increased numbers of factor XIIIa–positive dendritic cells (12 of 12). The absence of adnexal induction (0 of 16), the rarity of lesions with multinucleated cells (3 of 16) or epidermal hyperpigmentation (2 of 16), and the presence of S-100 immunoreactivity (16 of 16) and melanocytic proliferation (9 of 16) helped differentiate desmoplastic nevi from dermatofibromas. The similarities between desmoplastic nevi and desmoplastic melanomas included the presence of atypical cells (16 of 16) and HMB-45 expression in the superficial portion of the lesions (11 of 16). The infrequent location on the head or neck (1 of 16), the absence of mitotic figures (0 of 16), a significantly lower number of Ki-67–reactive cells, and a decrease in HMB-45 expression in the deep area of the lesions (8 of 11) helped distinguish desmoplastic nevi from desmoplastic melanoma. Desmoplastic nevi had overlapping features with hypopigmented blue nevi, but features tending to favor the latter included a predominance of ovoid nuclei, higher numbers of atypical cells, and homogeneous staining with HMB-45. We conclude that a combination of histologic and immunohistochemical criteria facilitates the reliable diagnosis of desmoplastic nevus from its simulators. © 1999 Lippincott Williams & Wilkins, Inc.