Progressive multifocal leukoencephalopathy: unusual MR findings

A case of progressive multifocal leukoencephalopathy (PML) with a classic clinical presentation but with unusual pathological and radiographic findings is reported. The pathology revealed evidence of prior hemorrhage, and imaging studies revealed focal cerebral atrophy as well as contrast enhancement on MR scans. The contrast enhancement was visible only by utilizing magnetization transfer pulses on T1-weighted scans. The case report indicates that image criteria for PML may need to be redefined in the future.