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Dermatofibrosarcoma protuberans (DFSP) is a rare, low- to intermediate-grade cutaneous soft tissue sarcoma of fibroblastic origin. It arises in the dermis and infiltrates subcutaneous fat, muscle, and fascia. Though locally aggressive with high recurrence risk, it has low metastatic potential.

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Epidemiology

• Incidence: 4–5 per million/year.
• Age: young to middle-aged adults (20–50 years).
• No strong sex predilection.
• Sites: trunk (most common, ~50%), proximal extremities, head & neck.

Etiopathogenesis

• Genetic hallmark:
  • Translocation t(17;22)(q22;q13) → COL1A1–PDGFB fusion gene.
  • Leads to constitutive PDGFB signaling and fibroblastic proliferation.
• Risk factors: trauma or prior radiation sometimes implicated.

Pathology

• Gross: firm, nodular cutaneous/subcutaneous mass, skin-colored to reddish, protuberant.
• Microscopy: storiform (cartwheel) pattern of uniform spindle cells infiltrating dermis and fat (“honeycomb pattern”).
• Immunohistochemistry: CD34 positive, factor XIIIa negative (helps differentiate from dermatofibroma).

Clinical Features

• Slow-growing, painless nodular skin lesion.
• Often mistaken for benign lesions (lipoma, dermatofibroma, keloid).