A case of an eight-year-old with signs of a pineal region tumor who underwent radical removal of a totally thrombosed vein of Galen aneurysm through the infratentorial supracerebellar approach. Pathophysiology of vein of Galen malformations including variety of clinical course, angiographic appearance and prognosis was described. Predisposition to spontaneous thrombosis in that type of malformations indicates necessity of taking into account such cases in the differential diagnosis of pineal region tumors.