Gliomatosis cerebri with secondary glioblastoma formation: report of two cases.

The clinicopathological features of two cases of gliomatosis cerebri associated with secondary glioblastoma formation are reported. In both cases, glial cells were diffusely distributed in the supra- and infratentorial regions and underlying brain structures were preserved from the onset. In spite of such diffuse distribution of neoplastic glial cells, similar to that observed in low-grade astrocytoma, in both cases the tumor underwent complete remission after radiotherapy. However, the tumor recurred as a localized glioblastoma in both cases, 37 months (case 1) and 7 months (case 2) after the radiotherapy. In both cases, recurrence was accompanied by prominent dissemination of CSF. The recurrent tumors were radiation resistant, and the patients' conditions deteriorated rapidly after recurrence. The present two cases demonstrated that gliomatosis cerebri, classified among brain tumors of unknown origin by the World Health Organization, may transform into highly proliferative circumscribed tumors, in spite of their good response to radiotherapy. Examination of pathological features and their correlation with MRI findings may allow us to better understand the response to radiotherapy and the process of recurrence.