[A case of lymphocytic hypophysitis mimicking pituitary macroadenoma]

Lymphocytic hypophysitis is a rare autoimmune disease of the pituitary gland mimicking pituitary macroadenoma on magnetic resonance imaging (MRI). We encountered a 32-year-old female who presented with a typical pituitary macroadenoma causing sudden on-set of visual disturbance during her second pregnancy. She underwent an endonasal-transsphenoidal resection of the mass diagnosed as a non-secreting pituitary macroadenoma after a cesarean operation. Intraoperatively, the lesion was found to be extremely tough and mucinous, and apparently differed from pituitary adenoma. The frozen section revealed hypophysitis and we performed only a biopsy of the mass. Histopathological examination showed diffuse infiltrate of non-specific lymphocytes. Postoperatively, prednisolone was given for two weeks, her visual disturbance improved with radiologically marked shrinking of the lesion. This case illustrates the difficulty of differentiation of lymphocytic hypophysitis from pituitary macroadenoma, and we discuss the clinical features and the management of this disease.