Cutaneous desmoplastic melanoma: reappraisal of morphologic heterogeneity and prognostic factors.
Desmoplastic melanoma (DM) is a variant of melanoma, which may be confused with nonmelanocytic benign or malignant spindle cell proliferations. The histologic hallmark of DM is the presence of fusiform melanocytes dispersed in a prominent collagenous stroma. Phenotypic heterogeneity of DM is underrecognized. Desmoplasia may be prominent throughout the entire tumor ("pure" DM) or represent a portion of an otherwise nondesmoplastic melanoma ("combined" DM). We reviewed melanomas with desmoplasia from 92 patients seen at a single institution between 1980 and 2002. Fifty-five of the tumors were pure DM. Thirty-seven were classified as combined. Mean follow-up of patients was 46 months for those alive at the last follow-up. Univariate analysis of clinical and pathologic parameters revealed four significant variables for disease-free survival: Clark level (IV vs. V; P = 0.005), DM subtype (pure vs. combined; P = 0.01), tumor mitotic rate (<1, 1-4, >4 mitoses/mm; P = 0.01), and tumor thickness (<1 mm, 1-4 mm, >4 mm; P = 0.02). Only histologic subtype (P = 0.02) and Clark level (P = 0.05) were independently significant by Cox regression analysis. Our results indicate that distinguishing pure from combined forms of DM is clinically relevant for prognosis (pure forms being associated with longer disease-specific survival). Failure to make this distinction may account for conflicting reports in the literature on the biologic behavior and prognosis of DM.
Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. busamk@mskcc.org
Klaus J
KJ
Busam
Urvi
U
Mujumdar
Amanda J
AJ
Hummer
Jennifer
J
Nobrega
William G
WG
Hawkins
Daniel G
DG
Coit
Mary S
MS
Brady
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005355:Fibrosis / Q000473:pathology; D006801:Humans; D008297:Male; D008545:Melanoma / Q000401:mortality / Q000473:pathology*; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000401:mortality / Q000473:pathology*; D016019:Survival Analysis