LBODP076 Hypophysitis Misdiagnosed As Pituitary Macroadenoma During Pregnancy

INTRODUCTION: Surgical treatment of nonfunctioning symptomatic pituitary macroadenoma may be associated with significant morbidity and the need for long-term medications. In late pregnancy and the postpartum periods, lymphocytic hypophysitis can present as a pituitary macroadenoma. We present a rare case of a pregnant patient who underwent pituitary surgery for lymphocytic hypophysitis. CASE PRESENTATION: A 37-year-old woman was evaluated for headaches and double vision during the third trimester of her pregnancy. A visual field exam showed bitemporal hemianopsia. Brain magnetic resonance imaging (MRI) showed a 2 cm intrasellar tumor with suprasellar extension, interpreted as a pituitary macroadenoma. The patient underwent a cesarean section. Labs after delivery showed IGF-1: 153 ng/ml (79-259), LH: < 0.2 mIU/ml (1.9-12.8), FSH: 6.4 mIU/ ml (2.3-12.6), Prolactin: 4.3 ng/ml (2.2-30.3), and a low morning cortisol: 2.4 ug/dl (4.2- 22.4). Pituitary MRI with intravenous contrast found a stable pituitary macroadenoma with suprasellar extension compressing the optic chiasm and prechiasmatic optic nerves without evidence of apoplexy. She underwent image-guided endoscopic transsphenoidal resection of the pituitary mass. Postoperatively, she developed diabetes insipidus that was treated with desmopressin. She was treated with steroids for secondary adrenal insufficiency and levothyroxine for central hypothyroidism. The pathology report showed hypophysitis; a lymphoplasmacytic infiltrate identified within the specimen with increased IgG4 expression. Differential diagnoses included IgG4-related hypophysitis and lymphocytic hypophysitis with an IgG4-expressing plasma cell component. Serum IGG 4 was 62 mg/dl (normal: 2 - 96 mg/dl); however, patient was already on steroids. She has been requiring hydrocortisone, levothyroxine, and desmopressin. DISCUSSION: Lymphocytic hypophysitis often occurs in late pregnancy or the postpartum period. MRI usually shows a pituitary mass, mimicking an adenoma. However, differences between lymphocytic hypophysitis and pituitary adenoma, using different imaging techniques, have been described. Lymphocytic hypophysitis should be considered in the differential diagnosis of women presenting with pituitary enlargement in the peripartum period. These patients may benefit from conservative treatment with glucocorticoids based on clinical suspicion. Presentation: No date and time listed