Sections show a portion of tissue with two distinct histologic patterns. The first area is comprised of mature cartilaginous tissue which is mildly hypercellular. The chondrocytes show moderate nuclear atypia with nuclear membrane wrinkling and chromatin clumping. These nuclei are crowded, and some chondrocytes are multi-nucleated.
The second region is comprised of haphazardly arranged, highly atypical spindle cells. These cells have severe nuclear pleomorphism (1 - 2 - 3) with irregular nuclear membranes, clumped chromatin, and frequent mitoses. Focal features suggestive of malignant fibrous histiocytoma are present. These cells stain positively for S-100 protein and negatively for prostate specific antigen.