Periventricular cavernomas presenting with hydrocephalus and superficial siderosis are uncommon lesions. We report a rare case of one such periventricular cavernoma located in the peritrigonal location of the right lateral ventricle in a 26-year-old male who presented with progressive headache for 3 months. Magnetic resonance imaging showed heterogeneous lesion with “blooming” on susceptibility-weighted imaging and superficial siderosis due to repeated microhemorrhages. The lesion was resected and found histopathologically to be cavernoma. We present this uncommon lesion with a review of the literature.