ABSTRACT
Pleomorphic xantoastrocytoma (PXA) is a rare, circumscribed astrocytic tumor that usually occurs in the superficial cerebral hemispheres in children and young adults. Most patients have a favorable prognosis, but recurrence and malignant transformation have been reported. In diffuse gliomas, approximately one third demonstrate mutations of the RB gene. Low expression level and high activity of p27 are known to constitute an independent prognostic factor in patients with malignant gliomas, while p21 expressions have variable labeling ranges. The molecular and genetic basis for tumorigenesis and progression of PXA are still largely unknown. In this study, 13 PXAs were examined immunohistochemically for pRb, p21, and p27 expression. Nine PXAs expressed homogeneous pRb positivity in the most nuclei of the tumor cells. Four cases showed an abnormal pRb staining pattern. All PXAs were positive for nuclear expression of p21. Diffuse nuclear positivity of p27 was seen in 10 cases, focal in 2, and in 1 case was not present. The cases with focal and negative p27 nuclear expression had few pRb-positive nuclei. The majority of PXAs appear to have preserved pRb, p21, and p27 functions. Additional studies are necessary to investigate whether cases with altered pRb and p27 expressions are associated with increased risk of recurrence or malignant transformation.
Subject(s)
Astrocytoma/metabolism , Biomarkers, Tumor/analysis , Brain Neoplasms/metabolism , Cyclin-Dependent Kinase Inhibitor p21/metabolism , Cyclin-Dependent Kinase Inhibitor p27/metabolism , Retinoblastoma Protein/metabolism , Astrocytoma/genetics , Astrocytoma/pathology , Brain Neoplasms/genetics , Brain Neoplasms/pathology , Gene Expression , Genes, Retinoblastoma , Humans , ImmunohistochemistryABSTRACT
O vírus de Epstein-Barr (EBV) tem sido implicado numa série de neoplasias, das quais se destacam o carcinoma nasofaríngeo, o linfoma de Burkitt e a Doença de Hodgkin (DH). Ýs evidências clínico-epidemiológicas de sua participaçäo na DH juntou-se a demonstraçäo direta do EBV na célula de Reed-Sternberg, através de técnicas de biologia molecular, hibridizaçäo in situ (HIS) e imuno-histoquímica (IHQ). O papel do EBV parece mais importante no subtipo celularidade mista (DHCM), nos casos infantis e nos países de 3o. mundo. Com o objetivo de avaliar o perfil da DH infanto-juvenil no estado do Ceará e sua possível associaçäo com o EBV,34 casos de DH de pacientes desta regiäo, menores de 18 anos, foram selecionados. Foi realizada revisäo histológica dos linfonodos, IHQ com marcadores linfóides e LMP (latent membrane protein viral), e HIS para a detecçäo do genoma viral nas células RS. Conclui-se que no grupo infanto-juvenil do estado do Ceará há grande incidência da DH em crianças abaixo de 10 anos e acometimento mais frequente de linfonodos cervicais, sendo o subtipo mais comum a DHCM (64,7 por cento). Além disso, a DH infanto-juvenil no estado do Ceará está fortemente associada ao EBV, principalmente na sua forma DHCM (EBV foi detectado em 100 por cento dos casos de DHCM). HIS e IHQ säo técnicas de boa qualidade e adequadas para a pesquisa do EBV em nosso meio
