2018 Volume 58 Issue 7 Pages 989-995
Background. It has been reported that the incidence of Klinefelter syndrome is approximately 1 in 600 newborn males. However, there seem to be many people with Klinefelter syndrome who do not yet realize that they have the disease. In addition, it is often reported that Klinefelter syndrome is associated with malignancies. The incidence of malignant germ cell tumors among patients with this syndrome is also much higher than that in the general population. Case. An 18-year-old man presented with sudden-onset dyspnea and left chest pain. A massive mediastinal tumor was observed on computed tomography images, and core needle biopsies and blood test results led to a diagnosis of mixed germ cell tumor. In addition, we suspected Klinefelter syndrome in the patient because of his germ cell tumor, physical characteristics (tall and thin body, long arms and legs), and history of attention deficit hyperactivity disorder, all of which are strongly associated with the syndrome. Genetic examination results confirmed our suspicions, and the patient was diagnosed with Klinefelter syndrome. After completing his chemotherapy treatment, he underwent surgery. At the time of writing, the patient has had an uneventful postoperative course without recurrence for four years and two months. Conclusion. In males diagnosed with mediastinal germ cell tumor, an additional diagnosis of Klinefelter syndrome should be considered if the patient has the physical characteristics of said syndrome or a history of learning disability.
