Mixed pituitary adenoma-gangliocytoma in a female albino rat

A mixed intrasellar pituitary adenoma-gangliocytoma was found incidentally in an aged female Sprague-Dawley-derived rat. The animal was killed at the end of a 104-week carcinogenicity study. At necropsy, the pituitary fossa was occupied by a large, hemorrhagic nodule compressing and displacing the base of the brain. The lesion consisted of large areas of a prolactin-secreting adenoma surrounding a central island of gangliocytoma. In the latter, ganglion-like cells of varying size exhibited, occasionally, beta-tubulin and neurofilament protein immunoreactivity in their perikarya, while their cell processes expressed intense neurofilament immunoreactivity. Accompanying satellite cells in the neuropil immunostained for glial acidic and S-100 proteins. To the best of our knowledge, the presence of mixed pituitary adenoma-gangliocytoma has not been previously reported in rats.