Radiological Diagnosis

Mineralizing Microangiopathy

The CT shows dense bilaterally symmetrical areas of calcification at the grey-white interfaces, primarily in the frontal cerebral parenchyma, with accentuation of the white matter hypodensity in the cerebral hemispheres. No abnormal enhancement is seen.

Mineralizing microangiopathy is a distinctive histopathologic process involving the microvasculature of the CNS. This is usually seen following treatment with a combination of radiation and chemotherapy for the treatment of CNS neoplasms and ALL prophylaxis in child-hood [1]. The CT findings of mineralizing microangiopathy are dystrophic calcification at the corticomedullary junction, lentiform nucleus of the basal ganglia, corticomedullary junction and dentate nucleus of the cerebellum [2].

The areas of calcification may give paradoxically increased signal on T1W MRI due to a surface relaxation mechanism and decreased signal on T2W images [1].

The pathogenesis of various forms of methotrexate neurotoxicity is poorly understood. The best established are: high concentrations of methotrexate in the CSF, prolonged exposure of the brain to low CSF concentrations of methotrexate and alteration of the blood brain barrier by cranial radiotherapy. The last allows systematically administered anti-leukemic drugs to enter the brain which in turn leads to necrotic changes in the CNS white matter [3].