Cutaneous solitary fibrous tumor: a report of 2 cases and review of the literature.

Solitary fibrous tumor is an uncommon mesenchymal neoplasm that can arise in both pleural and extrapleural locations. Composed of spindled cells intimately admixed with collagen bundles arranged in a "patternless pattern," this heterogeneous tumor can mimic a variety of benign and malignant mesenchymal neoplasms. We present the histological and immunohistochemical findings of two primary cutaneous solitary fibrous tumors, discuss the differential diagnosis, and review the literature. Although solitary fibrous tumors in cutaneous and subcutaneous regions are extremely rare, it should be considered in the differential diagnosis of primary spindle cell neoplasms of the skin.