KRAS and BRAF genes in sporadic and hereditary syndromes: an evaluation of sebaceous lesions and keratoacanthomas

Abstract

Sebaceous lesions are characterized by unique and sometimes hundreds of lesions, usually on the face or surrounding areas. Middle-age and elderly, especially between 4th and 5th decades of life are affected, though occasionally appearing in puberty when associated with genetic diseases. Lesions are classified as sebaceous hyperplasia, sebaceous adenomas, sebaceomas, basal cell carcinomas with sebaceous differentiation and sebaceous carcinomas (ocular and extraocular). The association of sebaceous lesions and ceratoacanthomas to hereditary syndromes have been reported and named after Muir-Torre's Syndrome. It is an dominant autosomic syndrome, with cutaneous phenotypic characteristics associated to visceral malignancies, especially colorrectal cancer. Few evaluations of molecular alterations have been reported to better understand these lesions. The majority report the association of the sebaceous lesions to Muir-Torre syndrome. Sebaceous carcinomas linked to Lynch syndrome have Microsatelite Instability (MSI) similar to the colon adenocarcinomas in patiens bearing germinative mutations of DNA repair genes. Novel evaluations are necessary to better understand the development of these lesions. Braf mutation has been described in sebaceous hyperplasias, appearing to be related to the initial stages of carcinogenesis of sebaceous lesions as well as with melanocytic lesions of the skin. (AU)