Endocrine Abstracts

We present the case of a 37-year-old male who initially attended the endocrine clinic with a 12 month history of progressive weight gain, erectile dysfunction and occasional headaches. He had no significant past medical history and reported preserved sense of smell, making diagnosis of Kallmann syndrome unlikely. Clinical examination revealed BMI of 40 with abdominal and flank striae, but otherwise normal secondary sexual characteristics including normal beard growth and peripheral body hair. Initial biochemistry showed suppressed gonadotropins with low serum testosterone (0.9 nmol/l), low-normal free T4 (11 pmol/l) with normal TSH (1.1 mU/l), and a normal prolactin level (345 mU/l), raising suspicion of hypopituitarism. While awaiting further iinvestigations, he developed polyuria and polydipsia and was subsequently diagnosed with central diabetes insipidus. He was commenced on desmopressin, testosterone replacement, and thyroxine. CSF analysis, PET-CT, and rheumatological investigations (ANA, ANCA) were undertaken; autoimmune screens were negative. MRI of the pituitary revealed extensive nodular extra-axial enhancement involving the hypothalamic-pituitary axis, third ventricular floor, and extending posteriorly to involve the brainstem and upper spinal cord. The radiological differential included neurosarcoidosis, other granulomatous conditions (e.g., IgG4 disease), lymphoma, or metastases. Further systemic imaging (CT chest/abdomen/pelvis) showed bilateral hilar and mediastinal lymphadenopathy, with parenchymal lung changes and mild retroperitoneal lymphadenopathy. These findings were consistent with a granulomatous process, most likely sarcoidosis. He was referred to the respiratory team who confirmed the diagnosis of sarcoidosis and systemic corticosteroid and immunosuppressive therapy was initiated. This case highlights the diagnostic complexity of infiltrative hypothalamic-pituitary disease and the importance of a multidisciplinary approach. Neurosarcoidosis, though rare, should be considered in patients presenting with partial hypopituitarism and diabetes insipidus with characteristic imaging findings.