Detection of MDM2/CDK4 protein overexpression by IHC can be used by pathologists to diagnose WDLPS and DDLPS. Considering a strong and diffuse immunostaining pattern in most of the neoplastic cells achieves the best results in identifying these tumours.

-Medulloblastoma (MB) is the most common malignant brain tumor in childhood. The alterations found include: presence of oncoproteins p53 and HER2, elevated mitotic index, and presence of neuronal differentiation. The aim of this study was to determine the immunohistochemical expression of markers Ki-67, NeuN, synaptophysin, HER2 and p53 in 40 MB samples and their correlation with clinicopathologic parameters and survival. In 29 patients (72.5%), ≥20% of cells were positive for Ki-67. Males showed greater ki-67 expression (p=0.02) and smaller survival rates (p=0.002). NeuN and synaptophysin were negative in 16 (40%) and 8 (20%) cases, respectively. P53 was positive in 18 (45%) cases, with 11 (61%) weakly positive and 7 (39%) strongly positive. HER2 was positive in 23 (57.5%) of the samples and did not show statistical association with survival (p=0.07).KEy woRds: medulloblastoma, immunohistochemistry, Ki-67, NeuN, synaptophysin, HER2, p53, survival analysis. expressão imunoistoquímica dos marcadores ki-67, neun, sinaptofisina, p53 e her2 em meduloblastoma e sua correlação com os parâmetros clínico-patológicosResumo -Meduloblastoma (MB) é o tumor maligno encefálico mais freqüente na infância. dentre as alterações encontradas estão: a presença das oncoproteínas p53 e HER2, elevado índice mitótico e presença de diferenciação neuronal. o objetivo deste estudo foi determinar a expressão imunoistoquímica (IMQ) dos marcadores Ki-67, NeuN, sinaptofisina, HER2 e p53 em 40 amostras de MB, correlacionando-as com parâmetros clinicopatológicos e com a sobrevida. Vinte e nove pacientes (72,5%) apresentaram 20% ou mais das células positivas para Ki-67. os pacientes do sexo masculino apresentaram maior expressão do Ki-67 (p=0,02) e também menor sobrevida (p=0,002). NeuN e sinaptofisina foram negativos em 16 (40%) e 8 (20%) casos, respectivamente. P53 foi positivo em 18 (45%) casos, sendo 11 (61%) fracamente positivos e 7 (39%) fortemente positivos. HER2 foi positivo em 23 (57,5%) das amostras e não demonstrou associação estatística com a sobrevida (p=0.07).PAlAVRAs-cHAVE: meduloblastoma, imunoistoquímica, Ki-67, NeuN, sinaptofisina, HER2, p53, sobrevida. Medulloblastoma (MB) is the most common malignant brain tumor in children, accounting for about 20% of all primary tumors of the central nervous system (cNs), with a peak of incidence at 5-7 years-old. These tumors have an aggressive behavior and despite treatment, the 5-year survival rate is 60% 1,2 . For therapeutic and prognostic purposes, patients are divided in groups of high and low risk, according to the staging proposed by chang et al. (1969) 3 , age at the time of diagnosis, and presence of residual tumor 4,5 . A more accurate assessment of risk in children with MB can be done using a combination of clinical, histopathologic, and molecular prognostic factors 4,6,7 .

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MYC amplification is a frequent event in SCLC and is related to a short survival time. MYC amplification may be an independent prognostic factor for SCLC. Further studies are required to support this finding and clarify the role of MYC in SCLC tumorigenesis.

Our method showed good sensitivity/specificity to indicate the outcome of patients according to their cofilin immunocontent in biological samples. Its application in a retrospective cohort and the results presented here are an important step toward the validation process of cofilin-1 as a prognostic biomarker.