Solitary fibrous tumors belong to the category of fibroblastic tumors. On cut section, regardless of the site of origin, the lesions are usually well-circumscribed, nodular, firm, gray-white masses, occasionally with myxoid areas, hemorrhage, and necrosis.8 Regardless of location, the extrapleural tumors are histologically identical to those in the pleura, which are principally composed of spindle cells dispersed among elongated, thin, parallel collagen bands. The arrangement of the cells may vary from area to area in the same tumor. In some zones, they are arranged in short, ill-defined fascicles, whereas in others, they are arranged randomly in what has been described as a patternless pattern. The nuclei are small, and the tumor has little or no mitotic activity and only mild to moderate nuclear atypia. A characteristic feature of the lesion that usually suggests the diagnosis is the relatively striking areas of hyalinization. Artifactual “cracks” may develop between the cells and collagen or between groups of collagen fibers. Myxoid changes may be seen.