Microtubular aggregates in the rough endoplasmic reticulum of a myxoid chondrosarcoma.

A tumor with the light microscopic and histochemical characteristics of myxoid chondrosarcoma is examined ultrastructurally. Instead of the usual features of chondroblasts, the tumor cells exhibited prominent collections of long straight microtubules within the endoplasmic reticulum. This finding is compared with other previously reported tubular aggregates. The differential diagnosis and ultrastructure of myxoid chondrosarcoma are also discussed.