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.
Patient with a germline alteration of one of the MMR (MisMatch Repair) pathway genes (MLH1, PMS2, MSH2, MSH6) proven by constitutional genetic analysis (genetically authenticated Lynch syndrome).
Patient followed at Nîmes University Hospital.
Patient having given free and informed consent.
Person affiliated to or benefiting from a social security scheme.
Person under court protection, guardianship or curatorship.
A person who is unable to give consent.
Person for whom it is impossible to give informed information.
Single group
Sampling of suspected skin lesions (in accordance with good care practices).
Diagnostic testSampling of suspected skin lesions (in accordance with good care practices) and swabbing of skin microbiota.
Constitution of a biobank
GeneticCollection of previously excised cutaneous and deep tumour lesions kept in a public or private pathological anatomy facility for these patients
Prevalence of Muir-Torre syndrome (MTS) in the population of patients with Lynch syndrome
Proportion of patients with Muir-Torre Syndrome confirmed by the occurrence of a sebaceous tumor (sebaceous adenoma, sebaceoma, sebaceous carcinoma) or several keratoacanthomas among patients with Lynch Syndrome. These tumors may or may not have had the mismatch repair system analyzed by immunohistochemistry (analysis of the 4 antibodies MLH1, PMS2, MSH2, MSH6) or by molecular biology (search for microsatellite instability). If the mismatch repair system has been studied, it must be deficient and the proteins absent on immunohistochemistry must be consistent with the mutated gene in Lynch Syndrome. If a block or slides are still available, sebaceous skin tumors or keratoacanthomas will be re-evaluated at Nîmes University Hospital for confirmation of the diagnosis.
Dermatological clinical manifestations in patients with confirmed Lynch Syndrome
Presence of clinical dermatological signs associated with Lynch syndrome. YES/NO
Non-sebaceous skin lesions and Deep-seated tumors not belonging to the narrow spectrum of Lynch syndrome. Presence of antibody MLH1
Molecular analysis (MSI test) and immunohistochemical analysis. Presence of antibody MLH1 on other tumour tissues (YES/NO) to determine the mismatch repair deficient (or MSI = pathological) or proficient (or MSS = normal) status of these lesions (and thereby their link with Muir-Torre syndrome).
Non-sebaceous skin lesions and Deep-seated tumors not belonging to the narrow spectrum of Lynch syndrome. Presence of antibody PMS2
Molecular analysis (MSI test) and immunohistochemical analysis. Presence of antibody PMS2 on other tumour tissues (YES/NO) to determine the mismatch repair deficient (or MSI = pathological) or proficient (or MSS = normal) status of these lesions (and thereby their link with Muir-Torre syndrome).
Non-sebaceous skin lesions and Deep-seated tumors not belonging to the narrow spectrum of Lynch syndrome. Presence of antibody MSH2
Molecular analysis (MSI test) and immunohistochemical analysis. Presence of antibody MSH2 on other tumour tissues (YES/NO) to determine the mismatch repair deficient (or MSI = pathological) or proficient (or MSS = normal) status of these lesions (and thereby their link with Muir-Torre syndrome).
Constitution of a biobank
Collection of previously excised cutaneous and deep tumour lesions kept in a public or private pathological anatomy facility for these patients
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