[Infected and calcified chronic subdural hematoma presenting an attitude of acute hematoma on MRI: case report].

We report a case of calcified chronic subdural hematoma with unusual magnetic resonance imaging (MRI) findings. A 50-year-old male with no marked medical history presented with fever for two weeks. Computed tomography (CT) revealed a thick, calcified subdural hematoma of low-iso mixed density. MRI showed characteristic signals of hematoma in the acute stage. Total removal of the hematoma by craniotomy was performed after rapid deterioration of consciousness. At surgery, a muddy hematoma and a small amount of pus were seen within the calcified capsule. Diagnosis of infected and calcified chronic subdural hematoma was established. His symptoms were resolved completely within the following few months. As the mechanisms of delayed signal sequence of hematoma on MRI, we speculate existence of tissue hypoxia associated with infection and paramagnetic effects of free radicals and ions associated with inflammation, necrosis and calcification.