Isolated ACTH deficiency during single-agent pembrolizumab for squamous cell lung carcinoma: a case report.

This is a case of isolated ACTH deficiency possibly due to hypophysitis in a patient with advanced lung cancer, in whom recent routine examinations had shown unremarkable results. We therefore conclude that isolated ACTH deficiency can suddenly arise during pembrolizumab monotherapy, albeit probably only rarely. Caution should be exercised to make sure that adrenal insufficiency is recognized immediately in order to achieve swift recovery by steroid replacement.