Basal Cell Carcinoma of Skin, Site Unspecified

The main aim of this study is to determine the prevalence of Muir-Torre syndrome (MTS) in the population of patients with Lynch syndrome (LS) confirmed by genetic analysis. Other aims include describing the dermatological clinical manifestations of these patients in order to describe any possible new cutaneous manifestations of this syndrome. Another aim is to use molecular biology (microsatellite instability) and immunohistochemistry to analyze non-sebaceous skin lesions and deep-seated tumors that do not belong to the narrow spectrum of Lynch syndrome, and determine whether their occurrence in these patients is related to the genetic syndrome. The follow-up of these tumors (screening for new tumors) in patients with SL, as recommended by the learned societies, will also be evaluated. Finally, a biobank of cutaneous and deep tumour lesions in paraffin (retrospective) and smears of cutaneous lesions and healthy tissue (prospective) will be set up.