Large-cell medulloblastoma with arrestin-like protein expression.

We report a case of a cerebellar large-cell medulloblastoma in a 12-year-old patient. Despite a gross-total resection followed by a radiation therapy and then a chemotherapy, the death occurred 6 months later. The cyogenetic analysis showed an isochromosome 17q. Immunoreactivity for synaptophysin, neurofilaments, chromogranin and arrestin-like proteins was detected, whereas rhodopsin, vimentin, EMA and PAX-6 were negative. In this study, we demonstrate that large-cell medulloblastoma with translocation in chromosome 17q is a neuronal differentiated medulloblastoma with non-photoreceptor characterization. By reverse transcription and polymerase chain reaction (RT-PCR) method, using primers for beta1, beta2 and visual arrestin, we demonstrate corresponding mRNA for beta1, beta2 arrestin but not for visual arrestin. These results suggest that arrestin immunoreactivity in this tumor corresponds to non-visual arrestin. This case corresponds to a new entity of large-cell medulloblastoma. The potential role of a new marker linked to a beta2 adrenergic receptor needs further molecular characterization to be useful.