Atypical posterior reversible encephalopathy syndrome associated with Lenvatinib therapy in a patient with metastatic thyroid cancer—A case report

Posterior reversible encephalopathy syndrome (PRES) is a disorder of reversible subcortical vasogenic brain oedema in patients with acute neurological symptoms. Drug‐induced PRES has been described with the usage of drugs that target receptors regulating vascular permeability or altering immune response. Lenvatinib is a receptor tyrosine kinase inhibitor that inhibits the kinase activities of vascular endothelial growth factor receptors implicated in cancer progression in addition to their normal cellular functions. The oedema associated with PRES is a consequence of disruption of cerebral blood flow autoregulation. Herein, we present a case of a 77‐year‐old lady who was on treatment with Lenvatinib for metastatic thyroid cancer who subsequently developed PRES. Her clinical and radiological findings improved after discontinuing Lenvatinib and the patient was switched to a different drug and remains asymptomatic on the same. This is the first such report of atypical findings of PRES in a patient on Lenvatinib therapy. Recognition of this entity is crucial for timely withdrawal of the drug and prevent further morbidity and mortality.