Posterior Reversible Encephalopathy Syndrome as an Adverse Effect of Lenvatinib in a Patient with Papillary Thyroid Carcinoma: A Case Report.

Posterior reversible encephalopathy syndrome (PRES) is an uncommon transient neuroradiological phenomenon that develops vasogenic cerebral edema and could be caused by some pharmacological agents, such as molecular-specific target agents. Lenvatinib belongs to the tyrosine kinase inhibitors and was approved in 2015 for progressive locally advanced or metastatic thyroid cancer refractory to radioactive iodine (I-131) treatment. Herein, we present the case of a 65-year-old woman who, while receiving treatment with lenvatinib for radioiodine-refractory metastatic papillary thyroid carcinoma, developed PRES without hypertension at the initial evaluation. Her clinical and radiological findings improved after withdrawing from the mentioned therapy, and later it was possible to re-incorporate lower doses of the medication, as described in the other three case reports found in the worldwide medical literature. The recognition of this entity is essential to timely suspend the drug and avoid greater comorbidity. This is the first paper reporting this kind of adverse event using lenvatinib in a Hispanic population.