Endocrine Abstracts

Background: Lymphocytic hypophysitis is a rare pathology of the pituitary gland which presents with features of hypopituitarism due to inflammation of the pituitary gland and/or a sellar mass lesion. It is an autoimmune condition and is the most frequent histopathological subtype of primary hypophysitis. Given that it is relatively rare, diagnosis and treatment can be challenging.

Case Description: A 60-years-old female with history of type 2 diabetes referred to endocrinology team with severe fatigue, generalised arthralgia, polyuria (6 l/da), polydipsia(3-6 l/day) and nocturia (4-6 times/day). Initially she was reviewed by ophthalmology team for Right 6th cranial nerve palsy which was initially assumed to microvascular complication related to her diabetes, but in view of her recent headaches since the palsy started, an MRI scan was arranged which showed bulky Pituitary gland. A referral was made to endocrinology team for further review. A dedicated Pituitary MRI scan was advised which showed enlargement of the pituitary mass with extension into the cavernous sinuses and quite a lot of surrounding dural inflammation, with no optic chiasm involvement. Reference laboratory results revealed raised Serum Osmolality (302 mosmol/kg; normal range 275–295 mosmol/kg), Urine Osmolality (280 mosmol/kg) and serum sodium (141 mmol/l; normal range 133–146 mmol/l), other pituitary hormones profile were unrevealing. Her only endocrine deficit is of ADH, resulting in diabetes insipidus. This has responded well to a low dose of desmopressin (DDAVP) of 50 mg TDS at the beginning but later it needed titration up. This has controlled her thirst well and prevented nocturia. She was referred to pituitary MDT for consideration of a pituitary biopsy. Histology was proved to be Lymphocytic hypophysitis with a low mitotic index. High dose of prednisolone 40 mg daily was started to try and supress the inflammation. Later, repeat MRI has shown significant improvement, with normal pituitary appearances now and resolved right 6th cranial nerve palsy.

Conclusion: It is important to have a wide differential diagnosis when managing pituitary masses. Clinical correlation with atypical MRI findings is useful to determine the diagnosis of LH.