Background:
Immune checkpoint inhibitor (ICI) therapy is an efficacious treatment for many malignancies. Hypophysitis is a side effect of ICI agents, where immune activation results in autoimmune off-target effects (1). Magnetic resonance imaging (MRI) has been a recommended investigation in its management (2, 3).
Aims:
To identify the frequency of identifiable MRI changes in the investigation of ICI-related hypophysitis. Methods:
A retrospective case-control audit was performed of all individuals who received one or more ICI between January 2018 and December 2023 at a single tertiary referral centre in Melbourne. Individuals requiring hormone supplementation were screened for a diagnosis of hypophysitis. A randomly selected control group demonstrated normal pituitary function at the time of MRI.
Results:
Fifty-four (6.9%) of 778 individuals who received ICI therapy were diagnosed with hypophysitis, 43 of whom had an MRI examining the pituitary gland within 2 months. Four (9.3%) had an initial report consistent with hypophysitis. Upon reexamination by an MRI-Fellowship trained Radiologist, a further 6 (total 10, 23.3%) had abnormalities consistent with acute hypophysitis. Among the control group, 45 of 46 individuals had an MRI within 2 months of normal pituitary biochemistry. All had an initial normal MRI report, but 1 (2.2%) had abnormalities consistent with hypophysitis upon review.
The hypophysitis and control groups had similar demographic characteristics and no additional pituitary pathology was noted on MRI in either group. In both groups, melanoma was the most treated malignancy, with nivolumab the most prescribed immunotherapy.
Within the hypophysitis cohort, common symptoms at presentation included fatigue, gastrointestinal symptoms, and headache, with central hypoadrenalism being the most frequent biochemical abnormality.
Conclusion:
Hypophysitis is an important complication of ICI treatment requiring prompt hormone supplementation (3). MRI provides minimal additional clinically meaningful information, so it could be reserved for atypical cases or those with persisting symptoms despite adequate supplementation.