MRI features in children with desmoplastic medulloblastoma.

Desmoplastic medulloblastoma (DMB) is a variant that has a more favorable prognosis compared to classical medulloblastoma, but its MRI features have not been as well described. We retrospectively reviewed the MRI features in children with pathologically proven DMB, including T2-weighted, fluid-attenuated inversion recovery (FLAIR) and contrast enhanced images, with isotropic diffusion-weighted (DW) MRI also performed in some patients. There were 16 tumors in 12 patients; one patient had five discrete lesions. In all patients, the tumor involved the cerebellar vermis, with nine lesions showing multiple peripheral small cysts. In nine of 16 tumors, there were focal areas of isointensity or hypointensity on T2-weighted or FLAIR images; seven of these showed corresponding focal enhancement. There was also one patient with radiating star-shaped enhancement in two lesions, and a multi-nodular enhancing pattern was observed in another patient. Low apparent diffusion coefficient (ADC) values were found in the lesions studied by DW MRI in five patients. DMB may have a typical imaging appearance of peripheral cysts, decreased ADC and focal enhancing areas corresponding to focal isointense or hypointense signal on T2-weighted and FLAIR images. Although these MRI features may distinguish this variant of medulloblastoma, multinodular or star-shaped radiating enhancement may also be detected in some patients.