Myxoma of bone in a nonhuman primate.

A myxoma of the mandibles in an adult female Macaca mulatta is described. The left mandible was markedly enlarged by the tumor, which extended from the symphysis to the temporomandibular joint. The tumor had extended a short distance across the symphysis into the right mandible. It was composed of a glistening mucinous material. Radiographs of the tumor showed a large expansile radiolucent lesion of the left mandible without soft tissue involvement. Light microscopy demonstrated capillaries, stellate shaped cells with processes up to 15 mu long, very few other cell types, and an amorphous ground substance. Electron microscopic examination revealed similarity to the myxoma of bone of man. The oxytalan fibers discovered in this myxoma have not been found in myxomas before and suggest the tumor is odontogenic in origin. The incidence of spontaneous neoplasia in general and that of spontaneous oral tumors in particular in nonhuman primates are reviewed.