Avaliação da imunoexpressão de BAP1, ALK, ROS1 e P16 em neoplasias melanocíticas spitzoides

• Autor(a) principal: Cardili, Leonardo [UNIFESP]
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5425903; http://repositorio.unifesp.br/handle/11600/50477
• topic: Spitzoid; BAP1; ROS1; ALK; P16; Nevus, epithelioid and spindle cell; Immunohistochemistry; Nevus, pigmented; Spitzoide; BAP1; ROS1; ALK; P16; Nevo de células epitelioides e fusiformes; Imuno-histoquímica; Nevo pigmentado

Introduction. Spitzoid tumors represent a heterogeneous group of melanocytic neoplasms. In recent years, several advances in Molecular Biology afforded significant discoveries on the pathogenesis and the biological behavior of these tumors. The BAP1 inactivation, the presence of kinase fusion related-proteins and the role of p16 protein are among the main criteria launched by new classification proposals and represent innovative markers with potential clinical significance. Objetive. To evaluate the immunohistochemical expression of BAP1, ALK, ROS1 and p16 proteins in spitzoid tumors. Methods. Retrospective study based on 47 tissue samples fixed in formalin and embedded in paraffin. This series was composed by the Pathology archives of three cancer reference institutions in the state of São Paulo, Brazil. Clinical-demographic data, histopathological aspects and immunohistochemical results for BAP1, ALK, ROS1 and p16 were studied in this case series composed by 27 Spitz nevus (NS), 15 Atypical Spitzoid Tumors (AST) and 5 Spitzoid Melanomas (MS). Results. Medium age was 21.2 years. Medium histological tumoral width was 5.7 millimeters. We observed statistical significance between diagnostic categories and age, width, mitotic index, ulceration, atypia, loss of maturation and the presence of giant cells. The global frequency of BAP1- inactivated tumors was 4.3% (02/46), both of them AST. The proportional frequency of BAP1-inactivated cases in AST group was 14.2% (02/14). We found no immunostaining for ALK and ROS1 in any out of 47 studied cases. We also did not observe a statistically significant correlation between loss of immunoexpression of p16 and non-benign categories. Conclusions. Age, width and mitotic index were significant diagnostic criteria to differentiate between MS and the remaining categories. Ulceration, atypia, loss of maturation and the presence of giant cells were significant diagnostic criteria to differentiate benign lesions (NS) and non-benignlesions (AST and MS). The loss of nuclear immunoexpression of BAP1 was exclusive to the AST category. We did not observe immunoexpression of ALK or ROS1 in any case. The immunohistochemical evaluation of p16 protein did not allowed differentiation between benign tumors (NS) and non-benign tumors (AST and MS).