Granular cell tumor of the pituitary stalk. Case report.

The case is described of a granular cell tumor of the pituitary stalk in a 40-year-old woman with secondary amenorrhea. A computerized tomography scan showed a large contrast-enhancing mass, and T1-weighted magnetic resonance images demonstrated a tumor isointense to the brain parenchyma with nonhomogeneous enhancement after intravenous administration of gadolinium diethylenetriamine penta-acetic acid. Histopathological examination, especially immunocytochemical and electron microscopic studies, showed elements supporting an astrocytic origin for this type of tumor, a hypothesis advanced by many authors but still controversial.