Chondrosarcoma in the Optic Canal: —A Case Report with Ultrastructural Study—

A rare case of primary low grade chondrosarcoma in the optic canal is presented. The fine structure of the tumor is generally that of a differentiated cartilage. The neoplastic cell cytoplasm has abundant glycogen granules, rough endoplasmic reticuli, Golgi apparatus and mitochondria. In the Golgi zone, secretory vacuoles frequently contain fine dense particles, associated with fine filamentous material, resembling the reticulated structure of extracellullar proteoglycans. Abundant mitochondria exist in the degenerated cells. Membrane invested matrix vesicles are frequently encountered in the amorphous material of disintegrated cells and in the vicinity of necrotic cells. Some of them may represent remnants of mitochondria. Intact neoplastic cells may secrete proteoglycans to make the chondroid matrix, while the degenerated tumor cells provide extracellular matrix vesicles for initial calcification.