Sinus pericranii: a scalp mass in a 6-month-old boy.

'Sinus pericranii' is an abnormal communication between the extracranial veins and the dural venous sinuses (usually the superior sagittal and the transverse sinuses). It is a rare childhood abnormality. We report a case of a 6-month-old boy presenting with a scalp swelling in the left parietal region. Ultrasound with color Doppler and MRI showed a dilated epicranial vein that communicated with the superior sagittal sinus. This anomalous venous connection is known as sinus pericranii. We describe the imaging findings, associated abnormalities and management of this rare vascular abnormality.