RESUMO
Medulloblastoma (MB) is the most common malignant brain tumor in children. It is currently classified in four main molecular subgroups with different clinical outcomes: sonic hedgehog, wingless, group 3, and group 4 (MBSHH, MBWNT, MBGRP3, or MBGRP4). Presently, a 22-gene expression panel has been efficiently applied for molecular subgrouping using nCounter technology. In this study, formalin-fixed, paraffin-embedded samples from 164 Brazilian medulloblastomas were evaluated, applying the 22-gene panel, and subclassified into the low and high expression of nine key medulloblastoma-related genes. In addition, TP53 mutation status was assessed using TruSight Tumor 15 Panel, and its correlation with expression and prognostic impact was evaluated. Samples from 149 of 164 patients (90%) were classified into MBSHH (47.7%), MBWNT (16.1%), MBGRP3 (15.4%), and MBGRP4 (20.8%). GNAS presented the highest expression levels, with higher expression in MBSHH. TP53, MYCN, SOX2, and MET were also up-regulated in MBSHH, whereas PTEN was up-regulated in MBGRP4. GNAS, TP53, and PTEN low expression was associated with the unfavorable patient outcome only for MBSHH (P = 0.04, P = 0.01, and P = 0.02, respectively). TP53 mutations were detected in 28.57% of MBSHH cases and exhibited association with lower expression and worse clinical outcome, although not statistically significant. The 22-gene panel for molecular classification of medulloblastoma associated with the expression of GNAS, TP53, and PTEN improves the patient prognostication in MBSHH subgroup and can be easily incorporated in the 22-gene panel without any additional costs.
Assuntos
Neoplasias Cerebelares/classificação , Neoplasias Cerebelares/genética , Cromograninas/genética , Subunidades alfa Gs de Proteínas de Ligação ao GTP/genética , Proteínas Hedgehog/genética , Meduloblastoma/classificação , Meduloblastoma/genética , PTEN Fosfo-Hidrolase/genética , Transcriptoma , Proteína Supressora de Tumor p53/genética , Adolescente , Brasil/epidemiologia , Neoplasias Cerebelares/epidemiologia , Criança , Pré-Escolar , Estudos de Coortes , Análise Mutacional de DNA/métodos , Feminino , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Lactente , Masculino , Meduloblastoma/epidemiologia , Mutação , Prognóstico , Adulto JovemRESUMO
Medulloblastoma has variable appearances on MRI in both children and adults. Adults are more likely to have heterogeneous cerebellar hemisphere tumours, and this is thought to be related to the greater prevalence of desmoplastic tumours in adulthood. Few studies have addressed the MRI features of adult medulloblastoma and the specific characteristics of desmoplastic and classic tumours have not been analysed. Our aim was to analyse the imaging characteristics of desmoplastic (DM) and classic (CM) medulloblastomas in adult. We retrospectively studied preoperative MRI of six men and three women, median age 33 years, range 23-53 years, with pathologically proved medulloblastomas. There were six (67%) with DM. The tumour was in the cerebellar hemisphere in eight patients (89%), including the three with CM, one of which was bilateral. All tumours were heterogeneous, giving predominantly low or isointense signal on T1- and isointense signal on T2-weighted images. Cystic or necrotic areas in all patients were particularly visible on T2-weighted images. Contrast enhancement was absent in one DM and varied from slight to intense in eight (three CM), homogeneous in one DM and patchy in seven. All tumours extended to the surface of the cerebellum and two had well-defined margins. MRI does not allow a clear distinction between DM and CM in adults.