Abstract
Hypercalcemia from tumors has been associated with Posterior Reversible Encephalopathy Syndrome (PRES) but the mechanism remains unclear. In this article, we describe a case of PRES caused by hypercalcemia from lymphoma. We summarize the available scientific evidence linking hypercalcemia to failure of cerebral autoregulation and potentially PRES. A major link is the hypomagnesemia induced by hypercalcemia. While this concept requires further clinical testing and validation, it is clinically significant for the management of PRES, even when not directly caused by hypercalcemia.