Primary intrapelvic seminoma in Klinefelter's syndrome.

Seminoma arising in patients with Klinefelter's syndrome is extremely rare; to our knowledge, only three cases have been reported in the English language literature. We report a case of intrapelvic seminoma in a 39-year-old man with Klinefelter's syndrome. Gross examination revealed that the tumor was a solid and irregular mass measuring 90 mm in diameter. The cut surfaces of this ill-defined tumor were yellow-white with necrotic foci. Histologically, the tumor cells were separated into lobules by branching, fibrous septa containing lymphocytes. In some parts of the tumor, a cord-like arrangement of tumor cells was present. Immunohistochemically, the tumor cells were strongly and diffusely positive for antiplacental alkaline phosphatase antibody along their cytoplasmic membranes, but negative for both chorionic gonadotrophin and alpha-fetoprotein. Based on these findings, we diagnosed this tumor as a seminoma. The testes when examined were found to be atrophic bilaterally, but with no tumor lesions. Chromosomal analysis yielded a 47XXY karyotype, compatible with Klinefelter's syndrome. These findings indicate a case of primary intrapelvic seminoma in Klinefelter's syndrome. The patient underwent intensive radiation therapy postoperatively, and he demonstrated no evidence of recurrence or metastasis during the 13-month period following surgery.