SUN-050 - Sarcoidosis with Hypothalamic-Pituitary Involvement as A Cause of Panhypopituitarism and Vasopressin Deficiency: Case Report

Introduction: Hypopituitarism can be congenital or acquired; the latter is usually associated with structural lesions , inflammatory, infiltrative, or infectious processes. Granulomatous diseases are an uncommon cause, with sarcoidosis being the most common at the systemic level. We present a case of systemic sarcoidosis with severe hypothalamic-pituitary involvement, highlighting the diagnostic and therapeutic challenges.

Case Presentation: A 23-year-old man presented with three months of polyuria, polydipsia, weight loss, and fatigue. Endocrinological evaluation revealed panhypopituitarism, with hypogonadotropic hypogonadism (total testosterone < 0.07 ng/mL), central hypothyroidism (FT4 0.9 ng/dL, TSH 0.04 μIU/mL), central adrenal insufficiency (cortisol 8 a.m. < 0.5 µg/dL, ACTH 5 pg/mL), low IGF-1 levels (87 ng/mL), and mild hyperprolactinemia (38 ng/mL), as well as arginine vasopressin deficiency, evidenced by hypernatremia (148 mEq/L), elevated plasma osmolality (305 mOsm/kg), and inappropriately low urinary osmolality (98 mOsm/kg). MRI showed a 16 × 7 × 6 mm infiltrative hypothalamic lesion with thickening of the pituitary stalk and absence of the hyperintense signal of the neurohypophysis. Transsphenoidal biopsy revealed noncaseating granulomas, with detection of nontuberculous mycobacteria by multiplex PCR. Additional studies demonstrated lymph node, skin, and lung involvement with a pattern typical of sarcoidosis. The patient began hormone replacement and antimicrobial treatment, with no radiological improvement; on the contrary, lesion progression was documented on neuroimaging. Finally, a diagnosis of systemic sarcoidosis with neurological involvement was established, responsible for panhypopituitarism and immunosuppression with corticosteroids and methotrexate was initiated, with subsequent clinical stability.

Discussion: Neurosarcoidosis with hypothalamic-pituitary involvement can manifest as panhypopituitarism and vasopressin deficiency, posing a diagnostic challenge due to its similarity to other infiltrative and infectious entities. The integration of characteristic radiological findings and histopathological confirmation of noncaseating granulomas is the key to confirm diagnosis.

Conclusion: Sarcoidosis with hypothalamic-pituitary involvement is a rare but clinically relevant entity among the causes of acquired hypopituitarism. This case highlights the need for a comprehensive diagnostic approach and hormone replacement therapy.

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