Clear cell chondrosarcoma: an ultrastructural study.

Clear cell chondrosarcoma (CCC) is a rare neoplasm. We report here a case of CCC. A 67-year-old Japanese man presented with right arthralgia for 1 year, and histological examination of the subsequent surgical resection of the right femoral bone showed the finding of CCC. Ultrastructurally, most organelles were observed in the perinuclear area. Clear neoplastic cells contained many glycogen particles in the area of the cytoplasm lacking organelles, although glycogen particles overall seemed to be evenly distributed in the cytoplasm. Some mitochondria, Golgi complex, actin-like filaments, and rough endoplasmic reticulum were also demonstrated in the cytoplasm of clear cells. Well-developed microvilli were also seen on the surface of neoplastic cells. These structures in neoplastic cells corresponded notably to structures of normal chondrocytes. Finally, our ultrastructural findings support further evidence that clear cells in CCC may show chondrocyte differentiation and a lack of an organelles area as well as abundant glycogen particles, may contribute to the clear cell morphology in CCC.