Brain stem vascular malformation simulating a hemorrhagic metastasis: report of a case with pathologic correlation.

A 65-year-old woman with known breast carcinoma developed headaches, followed shortly by disequilibrium, vertical diplopia and dysarthria. Cranial computerized tomography (CCT) demonstrated a dense, irregularly enhancing pontine lesion with associated mass effect. She received dexamethasone (Decadron) and radiotherapy and subsequently expired. Postmortem examination disclosed a ruptured brain stem arteriovenous malformation within a massive hemorrhage along with necrotic atypical cells suggestive of metastatic disease.