Pembrolizumab‐induced hypophysitis with acute progression of Rathke’s cyst

Abstract

AbstractImmune checkpoint inhibitor–induced hypophysitis is a rare complication of pembrolizumab, but the effects of drug‐induced hypophysitis on preexisting pituitary lesions are unknown. The authors treated an unusual case of pembrolizumab‐induced hypophysitis that resulted in acute exacerbation of a preexisting pituitary cystic lesion causing severe intractable headaches. Before initiation of pembrolizumab therapy, magnetic resonance imaging should be carefully reviewed for sellar pathology. Patients demonstrating a Rathke's cleft cyst should consider other forms of treatment first or be carefully counseled before pembrolizumab initiation, because the advent of hypophysitis could result in symptomatic progression of an existing lesion, necessitating urgent surgical intervention.