Two patients with rare causes of Weber's syndrome.

We report two patients with rare causes of Weber's syndrome and review the relevant literature. The first patient presented with Weber's syndrome caused by a partially thrombosed giant aneurysm of the posterior cerebral artery. The second patient was an immunocompetent patient who presented with progressive hemiparesis and subsequently developed Weber's syndrome. Primary central nervous system lymphoma (PCNSL) was eventually diagnosed. To our knowledge, the association between Weber's syndrome and PCNSL is rare.