FRI327 Lymphocytic Hypophysitis Presenting As Hypoprolactinemia In A Post-partum Female

Disclosure: J. John: None. S. Graybill: None. Lymphocytic hypophysitis is the most common presentation of primary pituitary gland inflammation. It typically presents with headache, vision changes, and sequelae of hypopituitarism, including central diabetes insipidus, anterior pituitary dysfunction, and hyperprolactinemia. Lymphocytic hypophysitis has a propensity to affect women in association with pregnancy due to an unknown underlying mechanism. A 38-year-old female presented with intractable headache and peripheral vision changes 3 weeks after giving birth to twin boys. Her post-partum course was complicated by preeclampsia with severe features. She also began experiencing blurry vision during this period. Seventeen days after delivery, she developed an acute onset headache and peripheral vision loss. She also noted sudden cessation of lactation with the onset of her headache. Initial CT head demonstrated a 1.6 centimeter enhancing pituitary mass suspicious for macroadenoma, and subsequent MRI sella revealed a 2.0 x 1.7 x 1.5 cm heterogeneously enhancing mass arising from the pituitary adenohypophysis extending to the undersurface of the optic chiasm. Initial laboratory evaluation demonstrated central hypothyroidism and inappropriately normal prolactin for a recently post-partum female. Given the patient’s impending vision loss, she was taken to the operating room for resection of suspected pituitary macroadenoma. Upon gross dissection, the abnormal appearance of the suspected mass prompted biopsy and immediate frozen section evaluation demonstrated significant lymphocytic infiltration. The resection was subsequently aborted. The patient was placed on levothyroxine and prednisone 80 milligrams daily for suspected lymphocytic hypophysitis, which was confirmed on tissue pathology. The patient’s headache and vision changes improved and after six days, she was discharged on a prednisone taper. Following three months of prednisone therapy, a repeat MRI sella demonstrated a reduction in the overall size of the pituitary gland to 1.7 x 1.2 x 1.1 cm. The patient was maintained on physiologic hydrocortisone and levothyroxine while monitoring for potential pituitary function recovery. Twelve months following her initial diagnosis, the patient did not demonstrate normalization of anterior pituitary function and required ongoing treatment for hypopituitarism. While hypoprolactinemia is atypical of hypophysitis, it is imperative to consider alternative pituitary pathology such as lymphocytic hypophysitis in the post-partum female when the clinical history is suspicious. Presentation: Friday, June 16, 2023