Organizing hematoma mimicking brain tumor

A 64-year-old man was referred to our hospital with progressive loss of function in his right upper and lower extremities. Unenhanced computed tomographic showed a high-density nodular lesion in the left basal ganglion with surrounding hypoattenuation. Brain magnetic resonance imaging demonstrated a predominantly cystic mass with multiple internal septa and an eccentric solid component showing enhancement. Histological examination revealed organizing blood clot and piloid gliosis. This unusual appearance of a mass-like organizing blood clot should be considered in the differential diagnosis when an encapsulated cystic mass with nodular component following the signal characteristics of old blood on MRI is encountered.