Diagnosis of a Dedifferentiated Chondrosarcoma of the Pelvis by Fine Needle Aspiration

Background Dedifferentiated chondrosarcomas account for approximately 10% of all chondrosarcomas. There are few reports that describe the cytologic findings in dedifferentiated chondrosarcomas. In all these cases it was only present in the smears as a high grade sarcoma component. Case A 58-year-old man with a bone lesion in the right acetabular zone was admitted to the hospital. The clinical diagnosis was chondrosarcoma. A fine needle aspiration biopsy was performed. The smears of the sample had different characteristics in composition. Some slides had mostly abundant chondroid matrix with low to moderate cellularity. Other slides were cellular and contained mainly pleomorphic, spindled-shaped cells. The typical appearance of dedifferentiated chondrosarcoma was present in some slides that showed focal zones with chondroid matrix adjacent to or surrounded by pleomorphic spindled cells. The composition of the surgical specimen (slightly greater cartilaginous component than the sarcomatous one) allowed us to make a straightforward diagnosis of dedifferentiated chondrosarcoma. Conclusion This is the first report that describes the presence of both components, high and low grade, by fine needle aspiration biopsy in dedifferentiated chondrosarcoma.