Background: Acute cases of Posterior Reversible Encephalopathy Syndrome (PRES) have highly characteristic MRI features. However atypical imaging fi ndings such as contrast enhancement in the acute setting can be misleading in patients with underlying disease that may have similar imaging features.
Case Report: We report three cases of acute PRES with mixed patterns of contrast enhancement on MR imaging. Each patient had an underlying pathology that could have similar imaging features, thereby potentially confounding the diagnosis of PRES (leukemia, metastatic disease and vasculitis).
Conclusions: Rapid diagnosis of PRES is essential to prevent complications such as infarction and hemorrhage. Proper diagnosis requires careful attention to the clinical and radiographic presentations. Although the MRI features of PRES are often highly characteristic, knowledge of atypical imaging features—such as acute contrast enhancement or unusual patterns of edema—is essential in preventing misdiagnosis. This is especially true in patients with an underlying disease process that may have similar imaging appearances.

Keywords: posterior reversible encephalopathy syndrome (PRES), hypertensive, encephalopathy