RESUMO
The etiology and pathogenesis of lentiginous acral melanomas are poorly understood. Recent studies have postulated that DNA repair mechanisms and cell growth pathways are involved in the development of melanoma, particularly changes in the MAPK pathways (RAS, BRAF, MEK 1/2, and ERK 1/2). The aim of this study is to assess the status of the MAP kinase pathways in the pathogenesis of acral melanomas. The authors examined the components of the RAS-RAF-MEK-ERK cascades by immunohistochemistry in a series of 16 primary acral melanomas by tissue microarray. The expression of MAP kinase cascade proteins changed in most cases. The authors observed that 57.14% of cases were BRAF positive and that 61.53%, 71.42%, and 71.42% of cases were positive for MEK2, ERK1, and ERK2, respectively; RAS was not expressed in 92.31%, and all cases were negative for MEK1. The absence of RAS and positivity for MEK2, ERK1, and ERK2 were most seen in invasive cases with high thickness. These aspects of the MAPK pathway require further examination in acral melanomas between different populations. Nevertheless, the results highlight significant alterations in the MAP kinase cascades that are related to histological indicators of prognosis in primary acral melanomas.
Assuntos
Biomarcadores Tumorais/análise , Sistema de Sinalização das MAP Quinases/fisiologia , Melanoma/metabolismo , Melanoma/patologia , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Análise Serial de Tecidos , Adulto JovemRESUMO
Oral mucosal melanoma is rare. Its incidence peaks between 41 and 60 years of age; male/female ratio is 2:1. Preferred oral sites include hard palate and maxillary gingiva. Risk factors have not been clearly identified, but pigmented lesions may be present before the diagnosis of oral melanoma. We report an unusual case of oral mucosal melanoma of long-standing duration on hard palate and maxillary alveolar ridge in a male patient. Histopathologic features confirmed the diagnosis of invasive melanoma with a prominent in situ component. A cell lineage derived from the tumor was established and characterized, with phenotypic markers of melanocytes.