Intra-operative 5-aminolevulinic acid (ALA)-induced fluorescence of medulloblastoma: Phenotypic variability and CD133+ expression according to different fluorescence patterns

5-Aminolevulinic acid (5-ALA) fluorescence has been proved advantageous in glioma surgery. Conflicting results have been reported by few studies published in literature about intra-operative 5-ALA-induced fluorescence of medulloblastoma (MDB). The aim of this study is to verify if these conflicting results could be explained by intra-tumoral histological and phenotypic differences. In the present case of a 45-year-old patient affected by a cerebellar MDB, histological analysis of cell phenotype and 5-ALA and CD133 correlation were performed in multiple samples according to different fluorescence patterns. Intra-operatively, the tumor appeared unevenly fluorescent under blue-violet light. Histologically, 5-ALA-intense biopsies from inner areas were characterized by a significant amount of cancer cells, whereas 5-ALA faint regions from peripheral areas displayed normal cerebellar features, with MDB cells infiltrating healthy tissues. Presenting our findings, we show the correlation between different 5-ALA fluorescence patterns of medulloblastoma with specific histological and phenotypical features. Thus, we hypothesize that a distinct relationship between CD133 expression and fluorescence accumulation presented in our study could partially explain the divergent results published in literature