MON-132 Panhypopituitarism Due To Pituitary Metastasis Of Renal Cell Carcinoma: A Case Report

Abstract Disclosure: N.R. Brott: None. L. Kandimalla: None. M. Hollie: None. Background: Pituitary metastases are rare (∼0.4% of intracranial metastases) and often asymptomatic. Over 60% originate from lung or breast cancer, while ∼2.6% arise from renal cell carcinoma (RCC). We present a rare case of panhypopituitarism due to pituitary metastasis from RCC. Case Report: A 65-year-old male with primary hypothyroidism and recent recurrence of RCC with stage 4 metastasis presented with shock and acute encephalopathy requiring intubation. He had reported headaches, fatigue, and lightheadedness. Seven months prior, an MRI showed a 2.4 cm pituitary mass, presumed to be a macroadenoma. MRI at admission showed interval growth to 3.2 cm with suprasellar extension, optic chiasm compression, hydrocephalus, and cavernous sinus invasion. Labs revealed panhypopituitarism: secondary adrenal insufficiency, central diabetes insipidus (CDI), hypogonadism, and low IGF-1, with mildly elevated prolactin. Pertinent labs included undetectable cortisol at 8 AM (Normal (N): 3.7-19.4mcg/dL), which peaked at 1.4 mcg/dL 60 minutes after administrations of ACTH; undetectable LH and Testosterone; low IGF-1 15 ng/ml (N: 64-240); elevated prolactin 15.68 ng/m (N: 2.64-13.13); TSH 3.3 uIU/ml (N: 0.34-5.60); free T4 0.60 ng/dL (N: 0.54-1.24); low total T3 37 ng/dL (N: 71-180); normal potassium, hypernatremia up to 164 mmol/L (N: 136-145) and inappropriately low urine osmolality at 132 mOsm/kg (N: 150-1150). He was stabilized with hydrocortisone and DDAVP, then underwent transsphenoidal resection. Pathology confirmed metastatic PAX-8-positive RCC. He was discharged with endocrinology and oncology follow-up. Discussion: Pituitary metastases usually occur between ages 60–70 and affect both sexes equally. Most are asymptomatic (93%). CDI is the most common symptom (∼45%), followed by ophthalmoplegia, hemianopsia, headache, fatigue, or hyperprolactinemia. Differentiating metastases from macroadenomas can be difficult—FDG-PET shows no clear distinction, and MRI may be nonspecific. Features suggesting metastasis include rapid growth, thickened stalk, cavernous sinus invasion, sclerotic sella, and suprasellar migration. Conclusion: RCC metastasis to the pituitary is rare but should be considered in cancer patients with new neurologic issues or signs of endocrinopathy. Early recognition enables appropriate endocrine and oncologic management. References: 1.Wendel C, Campitiello M, Plastino F, Eid N, Hennequin L, Quétin P, Longo R. Pituitary Metastasis from Renal Cell Carcinoma: Description of a Case Report. Am J Case Rep. 2017 Jan 3;18:7-11. doi: 10.12659/ajcr.901032. PMID: 28044054; PMCID: PMC5223779.2.Henry A, Nugent A, Wallace IR, Oladipo B, Sheehy O, Johnston PC. Pituitary metastasis: a clinical overview. Ulster Med J. 2021 Sep;90(3):146-150. Epub 2021 Nov 11. PMID: 34815592; PMCID: PMC8581691. Presentation: Monday, July 14, 2025