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May 2009

A Firm Red-Brown Plaque on the Arm—Diagnosis

Author Affiliations
 

MICHAEL E.MINGMD,MSCE

 

CARRIE ANN R.CUSACKMDSENAIT W.DYSONMDJACQUELINE M.JUNKINS-HOPKINSMDVINCENTLIUMDKARLA S.ROSENMANMD

Arch Dermatol. 2009;145(5):589-594. doi:10.1001/archdermatol.2009.88-b

Histopathologic evaluation revealed a plaquelike spindle-cell proliferation in the dermis and superficial subcutis. Under immunostaining, the tumor cells were strongly and diffusely CD34 positive. A few scattered melanin-containing spindle cells were S-100 protein and melan-A positive. The lesion extended to the side and focally to the deep margins. It was treated via Mohs micrographic surgery. There has been no recurrence to date.

Bednar tumors are melanin-containing variants of DFSP first described in 1957 by Bednar1 as storiform neurofibromas.2 Bednar tumors account for 1% to 5% of all DFSP and generally occur on the trunk or proximal extremities.2,3 Clinically, they usually present as a multinodular, firm, pigmented neoplasm. The surface may appear atrophic or sclerotic.2,4 Bednar tumors may occur in any race but tend to be more common in blacks, with an annual incidence that is approximately 7.5 times higher than that of whites.35 Incidence in male and female patients is approximately equal.3 While most cases occur in middle-aged adults, they can also develop in the very young and old.3,5,6 The mutation responsible for DFSP results from the rearrangement of chromosomes 17 and 22, which produces a fusion protein of collagen type 1 alpha 1 (COL1A1) and platelet-derived growth factor β (COL1A1-PDGFB).7 Tumor proliferation occurs to upregulated PDGFB and subsequent activation of the PDGF receptor tyrosine kinase.

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