We report the case of a B-cell type pituitary lymphoma in a 65 year-old male immunocompetent patient who presented with hypogonadotropic hypogonadism and central hypothyroidism and subsequently developed pulmonary lymphoma. Only three cases of pituitary lymphoma have been previously reported, one in a patient with acquired immunodeficiency syndrome, one case of T-cell lymphoma reported in the Japanese literature, and one case of B-cell lymphoma. The previously reported immunocompetent patients presented with signs and symptoms of optic chiasm compression as contrasted to our patient's endocrinologic presentation. B-cell lymphoma of the pituitary gland is a exceedingly rare though distinct clinical entity.