Histopathologic examination of formalin fixed paraffin embedded (FFPE) biopsied tissue from the presumed primary tumor site. (A) Low power (100x). Cellular tumor composed of spindled cells. (B) High power (400x). Short atypical spindle cells with few mitotic figures. Immunohistochemical studies reveal the tumor to be reactive for (C) S-100 protein and (D) CD34.