Clinical and radiological insights into secondary hypophysitis: A single-center experience with a focus on tuberculosis.

Purpose: Secondary hypophysitis (apart from immune checkpoint inhibitor [ICI] induced) is rare and is largely described in case series. We aim to describe the distinctive characteristics of the various etiologies of secondary hypophysitis from a single center.

Methods: A retrospective record review of 44 patients with secondary hypophysitis (excluding ICI) presenting to our institute between January 2002 and January 2023 was performed. The data of primary hypophysitis managed medically (n = 39) was retrieved from a prior publication and compared with common etiologies of secondary hypophysitis.

Results: The most common etiologies were histiocytic disorders - Langerhans cell histiocytosis (LCH) and Erdheim Chester disease (ECD) [n = 23] and tubercular hypophysitis (TH) [n = 10]. LCH/ECD were characterized by multisystem involvement, with arginine vasopressin deficiency (AVP-D) [22/23] being the predominant endocrine presentation. TH patients presented with mass effect (9/10), focal non-enhancing areas within an enhancing sellar/suprasellar mass on magnetic resonance imaging (MRI) (10/10), with evidence of tuberculosis elsewhere in 60%. Though caseating granulomas were universal on histopathology, bacteriological confirmation was negative in all pituitary specimens. When compared to primary hypophysitis, isolated infundibuloneurohypophysitis and AVP-D were more prevalent in LCH/ECD, while the presence of a sellar/suprasellar mass with focal non-enhancing areas was more frequent in TH. Furthermore, recovery of the hormonal axis upon follow-up was more common in primary hypophysitis.

Conclusion: Secondary hypophysitis in our cohort was predominantly histiocytic or tubercular in etiology, with LCH/ECD presenting largely with AVP-D and TH presenting with mass effects, focal non-enhancing areas, and paucibacillary disease.