[Extraskeletal myxoid chondrosarcoma: a clinicopathological study of six cases].

The clinicopathologic, ultrastructural, and immunohistochemical features of six cases of extraskeletal myxoid chondrosarcoma are described. Light microscopic examination disclosed a lobulated neoplasm consisting of cells that tended to be round or polygonal with plenty of eosinophilic cytoplasm. The tumor cells were arranged in strands and small nests surrounded by abundant myxoid extracellular matrix. Ultrastructurally, these tumor cells displayed the signs of chondroblastic differentiation. The cytoplasm contained numerous rough endoplasmic reticulum, mitochondria and scattered glycogen granules. The intercellular matrix showed amorphous material and electronic dense and fine granules. The tumor cells in all these six cases showed diffuse immunostaining for S-100 protein but were negative for keratin. The data obtained tend to support the chondroblastic origin of this tumor.