title: Muir-Torre syndrome or phenocopy? The value of the immunohistochemical expression of mismatch repair proteins in sebaceous tumors of immunocompromised patients.
abstract: Primary and secondary immunodepressive conditions are associated with an increased incidence of sebaceous tumors. Microsatellite instability (MSI) and lack of expression of mismatch repair (MMR) proteins, typical markers of Muir-Torre/Lynch heredo-familial settings, can be recognized also in immunocompromised patients. We aimed to carry on a systematic examination of clinical, immunohistochemical, biomolecular features of sebaceous tumors arising in immunocompromised and immunocompetent patients between 1986 and 2012. Microsatellite screening, immunohistochemical analysis and genetic testing were performed for hMLH1, hMSH2 and hMSH6. Methylation status of MMR genes was checked in cases with immunohistochemistry (IHC) loss of MMR proteins expression and no germline mutations. Fifteen patients had a personal history of visceral carcinomas fulfilling diagnostic criteria for Muir-Torre syndrome. In this cohort, IHC analysis, MSI status and genetic testing were in agreement, showing eight MSH2 and two MLH1 germline mutations. Five patients were immunosuppressed and their sebaceous tumors showed a lack of MSH2/MSH6 expression, although just one case with positive family history for visceral cancer harbored a germline mutation. In immunosuppressed patients, loss of IHC for MMR proteins is not necessarily secondary to MMR germline mutations. IHC false positives are probably due to epigenetic alterations. MSI and lack of expression of MMR proteins can be recognized also in immunocompromised patients without MMR germline mutations.
authors: Department of Clinical and Diagnostic Medicine and Public Health, University Hospital of Modena and Reggio Emilia, Via del Pozzo, 41100, Modena, Italy, giovanni.ponti@unimore.it.
authors: G
authors: G
authors: Ponti
authors: G
authors: G
authors: Pellacani
authors: C
authors: C
authors: Ruini
authors: A
authors: A
authors: Percesepe
authors: C
authors: C
authors: Longo
authors: V Desmond
authors: VD
authors: Mandel
authors: F
authors: F
authors: Crucianelli
authors: G
authors: G
authors: Gorelli
authors: A
authors: A
authors: Tomasi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D005260:Female; D006801:Humans; D016867:Immunocompromised Host / Q000235:genetics* / Q000276:immunology; D007150:Immunohistochemistry; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D055653:Muir-Torre Syndrome / Q000235:genetics*; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000096:biosynthesis; D009687:Nuclear Proteins / Q000096:biosynthesis; D010375:Pedigree; D012626:Sebaceous Gland Neoplasms / Q000235:genetics* / Q000276:immunology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009687:Nuclear Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein