Muir–Torre syndrome case associated with a hereditary MSH2 mutation

Muir–Torre syndrome combines skin tumors with sebaceous differentiation with malignant tumors of the gastrointestinal tract, which is caused by hereditary mutations in the genes of the mismatched nucleotide repair system. The article presents a clinical case of a 42-year old man who complained of an exophytic skin tumor on the back measuring 2.3 × 1.8 cm. At histological examination, the tumor was presented primarily with sebaceous differentiatied cells, which corresponded to adenoma of the sebaceous glands. From the patient’s history it became known that at the age of 37 he underwent hemicolectomy for high-differentiated adenocarcinoma. An immunohistochemical study with antibodies to proteins of the mismatched nucleotide repair system in a tumor sample revealed the absence of a nuclear reaction in tumor cells with antibodies to MLH1 and MSH2 proteins, which indicates the presence of germline mutations in these genes. High-throughput semiconductor parallel DNA sequencing revealed a variant of the nucleotide sequence in exon 12 of the MSH2 gene (c.1797_1801 del), leading to a shift in the reading frame (NM_000251: p.L599fs). Keywords: Muir–Torre syndrome, colorectal cancer, repair system, wrong-paired bases