A spontaneously occurring malignant pituicytoma in a male sprague dawley rat

Pituicytoma is an extremely rare neoplasm derived from pituicytes, which are glial cellsin the posterior lobe of the pituitary gland. A malignant pituicytoma was found in theintracranial cavity of a 55-week-old male Sprague-Dawley rat. Macroscopically, the tumorwas located on the sphenoid bone and involved the pituitary gland. The tumor was composedof sheets of fusiform cells with spindle- or pleomorphic-shaped nuclei and abundanteosinophilic cytoplasms. The cells were arranged in a whirling or irregular growthpattern. Some tumor cells were bizarre multinucleated giant cells with cytoplasmiceosinophilic hyaline droplets. Many tumor cells were strongly positive for vimentin andglial fibrillary acidic protein, and some cells were positive for ED-1 and S-100. Thesefindings closely resembled those of a giant cell glioblastoma derived from the pituitarygland, suggesting anaplastic pituicytoma. From our review of the literature, we believethis is the first report of a spontaneous malignant pituicytoma in a rodent.