THU109 An Interesting Case Of Infiltrative Panhypopituitarism Due To Metastatic Melanoma

Disclosure: N. Arora: None. C. Maxwell: None. J.M. Kim: None. Introduction: Metastases to the pituitary gland are a rare phenomenon only accounting for 1% of surgically treated pituitary tumors. The majority of cases, approximately 60%, in reported literature of hypopituitarism related to metastatic malignancy are associated with metastatic breast and lung cancer. These cases typically involve loss of posterior pituitary function rather than anterior. More specifically, the reported cases of panhypopituitarism related to melanoma have been associated with treatment with check point inhibitors with resultant hypophysitis. This case illustrates an unusual presentation of panhypopituitarism from direct infiltration and destruction of the pituitary gland from metastatic melanoma. Case Description: This was a 56-year-old post-menopausal female with a past medical history of Diabetes Mellitus type II who presented with a four-week history of generalized malaise, headache, dipoplia, and right eye ptosis. On physical exam, she was found to have right periorbital swelling, proptosis, and absent extraocular movement with right cranial nerve six palsy. MRI with pituitary protocol demonstrated a destructive, infiltrative process involving the pituitary, sella turcica, and cavernous sinus suggestive of either fungal infection or malignancy. Labs were indicative of panhypopituitarism including central hypothyroidism (TSH 0.008 uIU/mL, FT4 0.82 ng/dL), hypogonadism (FSH<17 mIU/mL; LH 0.3 mIU/mL), and low prolactin (0.3 ng/ml). Labs were also notable for a random low cortisol at 11AM (1.6 ug/dL, n>2.7ug/dl) and hyponatremia (125 mmol/L, n 135-146 mmol/L). A cosyntropin stimulation test failed to stimulate appropriately and stress dose steroids were initiated. A biopsy of the mass invading the pituitary gland was performed with pathology revealing metastatic melanoma with lymphovascular invasion. The patient’s hospital course was further complicated by multiple cerebral vascular infarcts, atrial fibrillation with rapid ventricular response, and heparin induced thrombocytopenia with rapid decline in functional status and patient soon passed. Post-mortem autopsy demonstrated friable hemorrhagic tissue (6.0 x 5.0 cm) involving the sellar and parasellar regions with diffuse lymphadenopathy consistent with metastatic melanoma. Discussion: This is a rare case of infiltrative metastatic melanoma with resultant panhypopituitarism. Although rare, metastatic disease should be considered when evaluating loss of pituitary function. Presentation: Thursday, June 15, 2023