“…1,4,5,[8][9][10]18,19) Giant pericallosal artery aneurysms are rarer, with only 15 cases reported. 1,2,[5][6][7][8][9][10][12][13][14][15]17,18,20) Giant aneurysms show a high incidence of thrombus formation, which causes difficulties in the differential diagnosis between giant aneurysms and other mass lesions including hematomas associated with vascular malformation and tumors based on cerebral angiography, computed tomography (CT), and magnetic resonance (MR) imaging. 2,10,12,14) We report a case of almost totally thrombosed giant pericallosal artery aneurysm that appeared to be recurring hematoma originating in a cavernous malformation or an avascular tumor with obliteration of the pericallosal artery on cerebral digital subtraction angiography (DSA), CT angiography, and MR imaging.…”