Spindle-cell lipoma of the skin

Spindle-cell lipoma of the skin is a distinct lesion that can occur in the dermis or subcutaneous tissue. The most important aspect of histologic differential diagnosis of this benign tumor is the exclusion of liposarcoma. We report two cases of spindle-cell lipoma, in which the clinical features of these lesions did not deviate appreciably from those of the usual lipomas. However, their microscopic appearances differed in terms of the distinctive spectrum of histological growth patterns. The clinical, immunohistochemical, and light and electron microscopic features of both cases were studied and compared with those of conventional lipoma and liposarcoma. Immunohistochemically both tumors showed no expression of insulin-like growth-factor receptors I and II. Coexpression of these receptors is usually observed in liposarcomas.