Lymphocytic hypophysitis. Associated with antiparietal cell antibodies and vitamin B12 deficiency.

Lymphocytic hypophysitis has been recognized as a distinct clinicopathologic entity. It is a cause of hypopituitarism in the postpartum period and is believed to have an autoimmune pathogenesis. We treated a patient with lymphocytic hypophysitis with two unique features. First, this patient had had a prolactin level of 101 ng/mL (normal, 0 to 25 ng/mL). To our knowledge, this degree of elevation has not been previously reported and is a level that might cause confusion with prolactin-secreting pituitary adenomas. Second, this patient had positive titers for antiparietal cell antibodies in conjunction with a low vitamin B12 level and anemia. To our knowledge, this is the first report of a clinically important autoantibody to extrapituitary tissue in a living patient with lymphocytic hypophysitis.