Dermatofibrosarcoma Protuberans of Distal Extremities and Acral Sites: A Clinicopathologic Analysis of 27 Cases

Dermatofibrosarcoma protuberans (DFSP) of the distal extremities and acral sites are extremely rare and incompletely characterized. Twenty-seven DFSP occurring in these sites were retrieved from our collective archives and reevaluated. Tumors occurred in 16 males and 11 females. Median age at presentation was 42.5 years (range, 7 to 78 y). Lesions involved the foot (18 with 6 in the toes and 2 on the plantar foot), distal ankle (4), hand (4 with 2 in the thumbs), and wrist (1). All cases showed predominantly classic DFSP morphology and were diffusely CD34 positive. Myxoid change, melanin pigmented, and giant cell fibroblastoma foci were each present in 1 case, respectively. Fibrosarcomatous change was present in 3 cases. Fluorescent in situ hybridization demonstrated PDGFB gene rearrangement in 9 of 10 tested cases. Clinical follow-up was available in 21 cases (median, 36.1 mo; range, 1 to 152 mo) and revealed 4 local recurrences. Four patients underwent digital amputation for unresectable recurrent disease. An additional patient underwent multiple resections with positive margins and elected to receive imatinib mesylate therapy. After a 2-year course, the patient has no evidence of residual disease (40 mo). No metastases were documented in any of the cases studied. The natural history of DFSP of distal extremities and acral sites is similar to that of its counterparts elsewhere. A high index of suspicion, careful morphologic examination for key histologic features of DFSP, and in selected cases, molecular studies to identify the pathognomonic COL1A1-PDGFB gene fusion should facilitate the distinction of these rare, locally aggressive neoplasms from morphologic mimics that may arise in distal extremities and acral sites. Presented at the London Dermatopathology Society Symposium, May 18, 2017. Supported by the SARC SPORE grant: U54 CA168512. Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Rajiv M. Patel, MD, 3261G Medical Science I, 1301 Catherine St., SPC 5602, Ann Arbor, MI 48109(e-mail: rajivpat@med.umich.edu). Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.

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