A squamous cell carcinoma in a young woman with Lynch syndrome.

Lynch syndrome (LS) is an autosomal-dominant inherited disorder characterized by a predisposition to colorectal cancer and extracolonic cancers (particularly endometrium, ovary, stomach, small bowel, hepatobiliary tract, pancreas, urothelial tract, brain, and skin). Muir-Torre syndrome (MTS) is considered a phenotypical variant of LS, where patients develop sebaceous neoplasms and keratoacanthomas. Currently, only few studies and case reports suggest an association between LS and other skin cancers, such as Bowens' disease, melanoma and squamous cell carcinoma (SCC). In this case-report we describe the case of a 33-year-old woman with LS and a proven MSH2 germline mutation, presenting with a SCC on the right cheek. Immunohistochemistry lacked MSH2 and MSH6 protein staining. The tumor showed a discordance between immunohistochemistry and micro-satellite instability status, for which a clear explanation cannot be provided yet. To conclude whether this pattern is indicative for SCC occurring in LS patients, further analyses of other LS patients presenting with SCC should be carried out. Our patient's young age and skin type (Fitzpatrick phototype VI) suggest a possible link between LS and cutaneous SCC.