Secukinumab, Pituitary Enlargement and Panhypopituitarism: Are They Related?

Pituitary adenomas are the most common cause of hypopituitarism associated with pituitary enlargement, but other aetiologies have been emerging, namely immune checkpoint inhibitor-induced hypophysitis (ipilimumab, nivolumab and pembrolizumab). Secukinumab is a recently approved human monoclonal antibody used for the treatment of psoriasis, with no know reported cases of hypophysitis. We describe a challenging case of panhypopituitarism in a patient with a pituitary incidentaloma and a temporal relationship between secukinumab initiation and the manifestation of clinical features suggestive of hypopituitarism. In such intricate work-up, the differential diagnoses should be carefully considered, taking into account the therapeutic and prognostic implications. LEARNING POINTS: Pituitary adenomas are the leading cause of hypopituitarism associated with pituitary enlargement, but clinicians should be aware of non-tumoural causes such as hypophysitis. Drug-induced hypophysitis has been described with immune checkpoint inhibitors used for diverse types of malignancies, but there is no evidence of an association between hypophysitis and the novel antipsoriatic agent, secukinumab. The differential diagnosis of hypopituitarism requires careful investigation so that management is appropriate and prognosis is improved.