Dermal pleomorphic liposarcoma resembling pleomorphic fibroma: report of a case and review of the literature.

Pleomorphic liposarcoma (PLPS) is a rare, high-grade sarcoma defined by the presence of pleomorphic lipoblasts. Constituting 5% of all liposarcomas, PLPS usually arises in deep soft tissues of the extremities, with rare occurrences in the dermis and subcutis. We describe a unique case of an 85-year-old Caucasian gentleman with a 1 year history of a pedunculated, pink, non-tender papule on the dorsum of his left arm, measuring 1.0 cm in maximum dimension. Biopsy revealed a dermal collection of atypical epithelioid and spindle cells superimposed on a sclerotic background, resembling a pleomorphic fibroma on low power. On high power, a central focus of discrete adipocytic differentiation with pleomorphic lipoblasts was present. Tumor cells were positive for S-100 and negative for desmin, actin, CD68, keratin, MART-1 and CD34. Clinicopathologic findings were consistent with PLPS and the diagnosis was made. PLPS is rarely localized to the dermis and one with low power features resembling a pleomorphic fibroma has not been previously described in the literature.