Hemorrhagic collision metastasis in a cerebral arteriovenous malformation.

A 26-year-old patient with recurrent choriocarcinoma of the testis presented with headache and progressive left homonymous hemianopsia. On initial MRI a grade 4 arteriovenous malformation (AVM) was identified in the right occipital lobe, which was further characterized by catheter angiography. Continued worsening of the headache in the following days prompted a follow-up MRI, which revealed a new T2 hypointense nodule and adjacent vasogenic edema in the periphery of the AVM. A follow-up MRI showed a marked increase in the size of the nodule with intrinsic enhancement and worsening perilesional edema. Based on the imaging evolution, the nodule was diagnosed as a metastasis and the patient was started on chemotherapy and radiotherapy. One week after the MRI he developed a sudden hemorrhage within the mass requiring decompression craniectomy and resection of both AVM and tumor. The histopathology of the resected mass confirmed the diagnosis of choriocarcinoma metastasis to the AVM. 2014 BMJ Publishing Group Ltd.