Testicular tumor in Down syndrome.

A 33-year-old male patient with Down syndrome, who stayed in a welfare institution, visited our hospital due to left testicular enlargement. He was diagnosed as having a left testicular tumor and underwent radical inguinal orchiectomy. Preoperatively, serum level of beta-human chorionic gonadotrophin (beta-HCG) increased to 0.9 ng/mL (normal range <0.2 ng/mL). For the last 2 years after orchiectomy, the serum level of beta-HCG remained normal. Histopathological examination of specimen revealed a typical seminoma. It is currently thought that risk of developing leukemia in patients with Down syndrome is 20- to 30-fold higher than that in normal subjects. Furthermore, the incidence of testicular cancer as a complication other than leukemia is expected to increase because of the increasing postpubertal population with Down syndrome.