Granular Cell Tumors of the Female Reproductive Tract in Wistar Rats

Abstract

Granular cell tumors were found in 18 female reproductive tract out of 300 Wistar rats. The tumor cells were histologically polygonal and arranged in sheets or cords separated from each other by collagenous septa. The cytoplasm was filled with periodic acid-Schiff reaction positive and diastase-resistant coarse granules, which showed electronmicroscopically characteristics of lysosomes. Metastatic lesions were not seen in any of the cases. The nest of tumor cells were occasionally embedded within the uterine stromal cells, and no discernible capsule was present. Immunohistochemically, they were positive for neuron specific enolase in all cases and vimentin in some cases, and negative for S-100, desmin or myoglobin in any of the cases. Biological relationship with meningeal granular cell tumors was not evident. These findings supported the notion of neuroectoderm origin of granular cell tumors in the female reproductive tract, and reminded us of a large variation of the tumor incidence among different colonies.