A Rare Case of Seminoma in an Elderly Patient With Suspected Lynch Syndrome

Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer, is caused by mutations in the mismatch repair genes and confers genetic predisposition to colorectal and other cancers. Germ cell tumors, the majority of which are seminomas, usually arise sporadically and predominantly occur in younger patients; their association with Lynch syndrome rarely occurs. Insight into such associations will provide knowledge about genetic predispositions and their management implications. A 56-year-old man was brought in with lower back pain and a testicle mass, and constant pain. Enlarged lymph nodes in the retroperitoneal and paravertebral regions suggested testicular cancer by CT scans. The right radical orchiectomy was performed for him and the tests proved that it was a classic seminoma. He had received four cycles of VIP chemotherapy because the cancer had extended to the lungs. The retroperitoneal lymph node dissection (RPLND) was performed after treatment because some lymph nodes were still enlarged, but no cancer was found in those nodes. Further examinations confirmed that the patient had anemia, and colorectal adenocarcinoma was the result of further investigations. The immunohistochemical analysis revealed that there was a loss of MSH6 protein expression while MLH1, MSH2, and PMS2 were preserved. These findings raise suspicion for Lynch syndrome. This case is interesting because seminoma and colorectal cancer were both identified in a patient with features suggestive of a hereditary cancer syndrome.