Endocrine Abstracts

JOINT3458

Introduction: Hypophysitis is a rare disease that affects mainly young adults. The main symptoms are headaches, pituitary insufficiency or vasopressin deficiency (AVP-D). Hypophysitis may be primary, secondary to systemic disease (sarcoidosis, L-group histiocytosis) or iatrogenic (mainly lead by checkpoint inhibitors). While hypophysitis may be part of a systemic disease at the onset, it may also precede it by several years.

Case report: A 38-year-old woman presented with a progressive onset of polyuria-polydipsia up to 9 litres per day. Diagnosis of AVP-D was quickly done after fluid restriction test, and desmopressin therapy was initiated leading to clinical improvement. She didn’t have pituitary insufficiency and didn’t exhibited any other symptoms such as headache or visual impairment. Pituitary MRI revealed thickening of the pituitary stalk associated with the loss of spontaneous T1 hypersignal of the posterior pituitary without symmetrical pituitary enlargement or extra-pituitary abnormality. A large clinical, biological and radiological workup didn’t identified any clues for systemic disease. More than two years after initial presentation, the patient noticed a clinically appearance of right parietal bone mass. Radiological assessment revealed a right frontal paramedial osseolytic osseomeningeal tissue process, presenting a great uptake in 18F-FDG PET CT. Bone biopsy highlighted a BRAF V600E positive Langerhans cell histiocytosis, leading to a Langerhans cell histiocytosis with pituitary and bone manifestation.

Discussion: This illustrate that the discovery of hypophysitis should prompt a search for systemic disease, at onset and during time, since hypophysitis may precede by several years a systemic disease. Particularly, Langerhans histiocytosis should be investigated in the presence of AVP-D, thickened stalk and absence of headache.