Object: Some medulloblastomas (MBs) are characterized by extreme nodularity and intranodular nuclear uniformity in a fine fibrillary background. These lesions have also been designated as "cerebellar neuroblastoma." Although numerous reports have been published in which their morphological features have been investigated, only a few studies have been focused on their neuroradiological appearance, biological behavior, and response to therapy. The goal of this study was to gather more information about these lesions.
Methods: The authors present 11 cases of MB with extensive nodularity. Five patients were boys and six were girls; all but one were 24 months of age or younger at diagnosis. Magnetic resonance imaging disclosed a peculiar grapelike architecture in eight cases. Surgical tumor removal was complete in nine cases and partial in one. In the other case a biopsy sample of the tumor was obtained after a preoperative course of chemotherapy. After surgery, two children were treated with radiotherapy alone and one with craniospinal irradiation followed by systemic chemotherapy. Eight patients were treated with chemotherapy only. All the patients in the study are presently alive with a median follow up of 66 months. Eight patients (73%) are in complete remission at 35 to 156 months. Three patients treated with chemotherapy alone postsurgery relapsed; however, all underwent successful retreatment (two with craniospinal irradiation and one with further surgery plus high-dose chemotherapy) and are in complete remission. A review of the literature revealed that patients in 11 of 12 reported cases were younger than 3 years of age and that seven of eight in whom follow-up information was available were alive and well, with survival times ranging from 6 to 84 months.
Conclusions: Medulloblastomas with extensive nodularity represent a variant that is characterized by: 1) occurrence in very young children; 2) a peculiar grapelike appearance on neuroimaging; and 3) an apparently favorable outcome.