[Beta-hCG-producing thymic teratoma: an uncommon cause of peripheral precocious puberty]

Among the causes of peripheral precocious puberty in men are the beta-human cho rionic gonadotropin (Β-HCG)-secreting tumors, such as hepatoblastomas, dysgerminomas, chorio carcinomas, and immature teratomas. In pediatrics, the mediastinal teratomas are rare, representing the 7-10% of extragonadal teratomas.

To describe the case of a patient with peripheral precocious puberty due to a Β-HCG -secreting thymic teratoma.

A seven-years-old schoolboy presents a three-months history of voice changes, gynecomastia, pubic hair appearance, and increased genital volume. In the exams, bone age of nine years, total testosterone 9.33ng/ml (< 0.4ng/ml), dehydroepiandrosterone sulfate (DHEAS), 17-hydroxyprogesterone (17-OHP), and normal adrenocorticotropic hormone (ACTH) test stand out; luteinizing hormone (LH) and follicle stimulating hormone (FSH) with low basal levels, Β-HCG 39.5mU/ml (< 2.5 mUI/ml), alpha feto protein (α-FP) 11,2ng/ml (0.6-2.0 ng/ml). Imaging study to determine the origin of Β-HCG secretion shows normal testicular ultrasound and thoracic, abdominal, and pelvic computerized axial tomo graphy (CAT); brain and sellar resonance without significant findings. The positron emission tomography/computed scan (PET SCAN) shows a tumor image in the anterosuperior mediastinum. The tumor is resected, and the biopsy shows an immature cystic teratoma in the thymus. Post-operatory evolution was satisfactory, with normalization of hormonal levels.

The appearance of a teratoma in a pediatric patient is rare, even more if it is immature, with thymic location and P-HCG- secretor. It is important to consider it within the differential diagnosis facing precocious puberty, as a better way to handle appropriately.