[Characteristics of medulloblastoma in children under age of three years]

We present a series of 51 medulloblastoma in children under three years, collected in N.N. Burdenko Neurosurgical Institute from 2000 to 2010. 57% of the tumors showed desmoplastic/nodular histology. Performed fluorescence in situ hybridization (FISH) analysis revealed the MYC oncogene amplification in 4%, the MYCN oncogene amplification - in 8%, isochromosome 17q - in 16% of cases. 9q deletion was found in 8% of desmoplastic/ nodular medulloblastomas. Our results showed that desmoplastic/nodular medulloblastoma has a positive predictive value for progression-free survival. Another feature of a biology of medulloblastomas in children younger than three years is the lack of nuclear accumulation of beta-catenin, and 6q deletion. Medulloblastomas with MYCN oncogene amplification often exhibit desmoplastic/nodular histology and a relatively favorable outcome. The most unfavorable prognostic marker is the MYC oncogene amplification, which in our series of 100% combined with the large cell/anaplastic medulloblastoma and isochromosome 17q - such tumors should be included in the "high risk" protocol.