Tophaceous pseudogout: a pitfall in the diagnosis of chondrosarcoma.

Tumoral calcium pyrophosphate dihydrate deposition disease (TCPPD, tumoral or tophaceous pseudogout) is a rare nonneoplastic entity which mimics soft-tissue or skeletal malignancy. We present here the fine-needle aspiration cytology findings of a unique case of TCPPD in a 76-yr-old woman, with a large paraischial soft-tissue mass diagnosed as a malignant neoplasm. The difficulty in diagnosing such lesions by fine-needle aspirates is discussed and reviewed in the context of known cases from the literature.