We report a rare occurrence of an intraparenchymal plasmocytoma. On the past history of a severe head injury twenty years ago and the presence of a porencephalic area on the computerized tomography scan and magnetic resonance imaging we suspected a possible trauma-tumor relation. Accuracy of the histological diagnosis of plasmocytoma was confirmed. The treatment was a surgical excision only, and after a 4.5 years follow-up period, no clinical nor radiographic recurrence was noted.