Lymphocytic hypophysitis simulating a pituitary adenoma in a nonpregnant woman.

Lymphocytic adenohypophysitis can cause pituitary expansion and hypopituitarism closely mimicking the features of a pituitary adenoma. In contrast to pituitary adenoma, lymphocytic adenohypophysitis occurs almost exclusively in young women in relation to pregnancy. We report a case of a 43-year-old nonpregnant nullipara who exhibited an intrasellar mass with diffuse homogeneous contrast enhancement on magnetic resonance imaging scanning. Serum hormone analyses revealed secondary hypoadrenalism, hypothyroidism, and hypogonadism. The patient underwent surgery for a presumed nonsecreting pituitary adenoma. Histopathological examination showed extensive infiltration of the anterior pituitary gland by chronic inflammatory cells. The immunohistochemical pattern of the inflammatory cells indicated the chronic and putatively autoimmune nature of the disease.