Pleomorphic lipoma. Case reports and review of the literature.

Two patients are reported with pleomorphic lipoma, a benign subcutaneous fatty tumor showing atypia in which histologic diagnosis may be difficult. The tumors are well circumscribed lesions, most commonly occurring in the neck and shoulder of middle aged men. An important histologic criteria is the presence of floret-like multinucleated giant cells embedded in a myxoid stroma. Pleomorphic lipoma may be confused with several malignant soft-tissue neoplasms, including myxoid malignant fibrous histiocytoma and variants of liposarcoma. It is important to establish the correct diagnosis to avoid unnecessary radical surgery.