Endocrine Abstracts

Background: Lymphocytic hypophysitis (LyH) is a rare autoimmune endocrinopathy. It is more common in peripartum women classically presenting with mass effect symptoms, hyperprolactinemia and symptoms of adenohypophyseal/neurohypophyseal involvement characteristically sparing the posterior pituitary. It is uncommon in the elderly, in whom it can present differently causing diagnostic dilemmas.

Clinical Case: A 68 year-old-woman presented with polydipsia, polyuria, xerostomia and weight loss since 3 weeks and had no headache or visual symptoms. She appeared dehydrated and hypernatremic with a serum Sodium level of 152 mmol/l (133 -146 mmol/l). Other routine blood tests were normal.Further biochemistry showed Serum Osmolality of 313(275-295 mosmol/kg) and Urine osmolality of 92(50-1200). Water deprivation test under close supervision, confirmed AVP-D. She responded well to Desmopressin. Prolactin was 810(109-557 mu/l). The rest of the pituitary hormones were normal. MRI pituitary fossa revealed 11 mm enhancing sellar lesion with thickened enhancing infundibulum suggestive of LyH. There was no history of malignancy, autoimmune/infiltrative/inflammatory disorders or immunotherapy which could have triggered LyH. Connective tissue screen, ACE levels, and tumor markers were negative. She awaits Respiratory input as her CT showed mediastinal lymphadenopathy with lung changes. Pituitary MDT outcome was that of hypophysitis rather than a mass lesion. Interval scan in 3 months’ time showed resolving hypophysitis.

Discussion: This is an atypical presentation of LyH and reinforces the importance of a multidisciplinary approach when dealing with a vaguely understood entity like LyH in order to avoid unnecessary diagnostic dilemmas and overzealous treatment. LyH is often self-limiting, but can lead to permanent endocrine deficiencies. Careful observation is warranted with hormonal replacement where indicated.

Conclusion: This is a rare and atypical presentation of LyH in a woman of non-reproductive age group with no pre-existing autoimmune or infiltrative pathology, presenting with isolated AVP deficiency.