Endocrine Abstracts

A 68-year-old male presented with fatigue and acute onset polyuria and polydipsia. There was no history of headaches, visual symptoms, previous cranial radiations, chemotherapy or CNS infections. Investigations revealed normal fasting glucose, urea, creatinine, liver functions and electrolytes including calcium. Further workup including pituitary profile, paired osmolalities and water deprivation test confirmed hypopituitarism and cranial diabetes insipidus (Table 1). The underlying aetiology remained unclear as initial MRI Pituitary; Iron studies and CT chest/abdomen/pelvis were unremarkable. He was started on desmopressin and hormone replacements with improvement in his symptoms. His 1-year follow-up MRI pituitary was also unremarkable and remained asymptomatic until 18 months post initial diagnosis, when he developed aggressive behaviour and confusion, prompting MRI brain which showed a large midline suprasellar lesion in the region of hypothalamus. Repeat CT chest/abdomen/pelvis did not reveal any metastatic disease. Endoscopic biopsy of hypothalamic lesion confirmed Langerhans cell Histiocytosis on histology. He received 4 cycles of Cladibrine with associated regression of lesion in MRI but no improvement in cognitive function. He eventually succumbed to chest sepsis during his last hospitalization. This case highlights a rare case of isolated presence of Langerhans cell histiocytosis in hypothalamic region presenting with adult onset central diabetes insipidus, eventually leading to panhypoituitarism. Retrospective review of images showed that a very small hypothalamic lesion may have been overlooked on his follow-up scan at 1 year. Increased vigilance is therefore required when evaluating imaging with focus on hypothalamic region in addition to pituitary gland.