Endocrine Abstracts

Introduction: Chronic autoimmune hypophysitis is a rare disorder characterised by prolonged inflammation of the pituitary gland, with the commonest subtype being lymphocytic hypophysitis. It is often associated with hypopituitarism and is exceedingly rare in the paediatric population. Here, the authors present a novel case of asymptomatic, chronic hypophysitis in a paediatric patient in association with juvenile idiopathic arthritis (JIA).

Case report: A 9 year-old Caucasian girl presented with a 4-month history of anterior uveitis, bilateral knee swelling and polyarthritis in the small joints. After a series of investigations, she was diagnosed with JIA (ANA positive, RF negative) and commenced on Adalimumab and Methotrexate treatment. An initial MRI orbit with contrast showed an enhancing mass centred within the pituitary fossa (10x11x13 mm), extending into the suprasellar cistern and superiorly displacing the pituitary stalk and optic chiasm. There was no associated hydrocephalus, bitemporal visual field defect or endocrine abnormality. Tumour markers (AFP, β-hCG) were negative. Genetic testing was negative for MEN1/AIP/CDKN1B/CDC73/ RET mutations. A biopsy was not performed due to potential damage to hypothalamo-pituitary function. Regular MRI scans over 2 years have shown no interval changes. Due to the diffuse pituitary enlargement and concomitant JIA, a provisional diagnosis of chronic autoimmune-related hypophysitis was made. This patient continues to undergo regular surveillance with yearly MRI scans.

Discussion: Lymphocytic hypophysitis in children can be either primary (often in association with other autoimmune disorders), or secondary (due to direct infiltration of the pituitary gland/stalk by tumours or other diseases e.g. Langerhans cell histiocytosis). Cases have been described in adults in association with rheumatoid arthritis, but none in children with JIA. Additionally, hypophysitis has been described in association with immune checkpoint inhibitors but not Adalimumab (anti-TNFα).

Conclusion: To the authors’ knowledge, this is the first incidence of chronic autoimmune hypophysitis secondary to JIA in the paediatric population. Although this presentation was entirely asymptomatic, symptoms and signs of hypothalamic/pituitary dysfunction in JIA patients should be investigated further and treated promptly.