Medulloblastoma with lipidized cells versus lipomatous medulloblastoma.

BACKGROUND: Lipomatous medulloblastoma is a recently identified clinicopathological entity, characterized by areas of lipomatous differentiation, manifestation in adults, and apparently by a favorable prognosis. MATERIAL AND METHODS: In our series of medulloblastomas of adults and children we have found lipidized cells within the tumor in 6 out of 78 cases of adults and in 8 out of 44 cases of children. In 3 adult cases and 3 children cases, lipidized cells were particularly numerous and clustered. RESULTS: Neuronal differentiation was found in 4/6 cases; no case showed GFAP-positive tumor cells. Lipidized cells were constantly immunopositive for vimentin and some of them also for KP-1 and CR3/43. The proliferation potential was evaluated by the immunohistochemical demonstration of MIB-1; MIB-1-labeling index (LI) ranged from 20.8% to 40.5%. No case survived longer than 7 years after diagnosis and postoperative radiotherapy. CONCLUSION: The present 6 cases of heavily lipidized medulloblastoma are not uniform as for age of occurrence, proliferation potential and survival. They do not share the clinical and pathologic features of 'lipomatous medulloblastoma'. Therefore, the finding of large numbers of lipidized cells in a medulloblastoma does not authorize to diagnose the tumor as 'lipomatous medulloblastoma', for which a favorable clinical prognosis is foreseen.