IMPE Abstracts

The reported incidence of extragonadal germ cell tumors (eGCT) in Klinefelter Syndrome (KS) patients is 1.5/1.000, a fifty-fold increase over the general population. A recent literature review describes fewer than 150 reported cases (Bonuvrie K et al, Int J Pediatr Endocrinol 2020). Mediastinum is the most prevalent localization of eGCT in pediatric patients with KS. Hormonal profile of these patients was not described in these series.

Case report: A 15 year old boy was diagnosed as a case of 47XXY Klinefelter syndrome. He presented bilateral gynecomastia, testicular volume of 5 ml. Laboratory assessment showed serum levels of FSH 19.9 mU/ml, LH 13.5 mU/ml, Testosterone 3.99 ng/ml, AMH 85.7 pg/ml, Estradiol 51 pg/ml. One year later he developed headache and weight loss (1.7 kg in 3 months) and the following laboratory studies were obtained: serum levels of FSH and LH <0.1 mU/ml, testosterone 4.9 ng/ml and estradiol 110 pg/ml. Due to the presence of suppressed gonadotropins, dosage of ꞵHGC was requested: 50340 mU/ml. Chest X-ray showed an anterior mediastinum mass. Brain magnetic resonance, abdominal and testicular ultrasound were normal. Positron emission tomography enable the visualization of an anterior mediastinum heterogeneous tumor of 88 mm in diameter and multiple lung nodules. He underwent four cycles of chemotherapy preoperatively and two cycles postoperatively with etoposide, ifosfamide, and carboplatin. Pathologic analysis demonstrated a germinal tumor (teratoma) with necrosis areas. After treatment, ꞵHCG values became negative and FSH and LH levels increased. He did not present late complications from the treatment.

Conclusion: gonadotropin monitoring allowed the suspicion of germ cell tumor in a patient with Klinefelter Syndrome.