Endocrine Abstracts

Introduction: Lymphocytic hypophysitis is an uncommon disease of the pituitary gland mimicking pituitary macroadenoma on magnetic resonance imaging (MRI).

Case: A 37-year-old female admitted to our clinic with headache, amenorrhea, polyuria and history of pituitary microadenoma. On laboratory examinations, prolactin level was mildly elevated (42 ng/ml) and FSH–LH levels were normal (2.4–4.04 mIU/ml) despite the low estrogen level (<20 pg/ml). Water deprivation test confirmed central diabetes insipidus (DI). Pituitary magnetic resonance imaging revealed an 16 mm hemorrhagic macroadenoma with partial compression over optic chiasma. Patient underwent a transnasal/transphenoidal resection of the mass. Histopathology was suggestive of lymphocytic hypophysitis with diffuse infiltrate of predominantly B lymphocytes. After the surgical approach, her prolactin level was normal but diabetes insipidus and hypogonadotrophic hypogonadism persisted.

Discussion: Differential diagnosis of lymphocytic hypophysitis may be difficult because of its presentation as an expanding pituitary adenoma. Besides hemorrhagic appearance of lymphocytic hypophysitis on pituitary MRI is rarely reported.