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Case Reports

Abstract

Dermatofibrosarcoma protuberans (DFSP) is a slow-growing dermal tumor exhibiting diverse histologic morphology, including sclerosing, pigmented, myxoid, atrophic, and fibrosarcomatous variants. Partial biopsies, particularly of the sclerosing variant, can easily be misdiagnosed as benign lesions such as sclerotic fibroma, or perineurioma, underscoring the importance of clinical correlation and complete excision for accurate diagnosis.

We report a 48-year-old man presenting with a presumptive hypertrophic scar over the right middle chest, present for at least 20 years. He recalled multiple biopsies previously revealed unknown benign diagnosis. Recently, the lesion had become symptomatic, enlarging to 14 × 10 cm with central ulceration with a 3 cm polypoid portion. Biopsy revealed spindle cells within a dense fibrotic matrix, positive for CD34 and focally faint EMA, but negative for SOX10, S100, desmin, SMA, and STAT6. No COL1A1::PDGFB fusion was detected via a 64-gene assay. Therefore, the initial diagnosis of atypical spindle cell neoplasm was given. Given clinicopathologic suspicion, extensive excision was undertaken, demonstrating a storiform arrangement of monotonous spindle cells, uniformly positive for CD34, but negative for EMA, factor XIIIa, S100, ALK, and STAT6, confirming the diagnosis of DFSP with sclerosing feature.

This case illustrates diagnostic challenges posed by the sclerosing DFSP variant, particularly when initial superficial biopsies lack distinctive genetic rearrangements and IHC profiles cannot distinguish among differential diagnoses. It emphasizes the necessity of thorough clinicopathologic evaluation, considering broad differential diagnoses and ensuring complete tumor assessment through excision to facilitate definitive diagnosis and effective clinical management.