Leydig cell tumour-induced bilateral gynaecomastia in a young man: endocrine abnormalities.

Among the various causes of gynaecomastia, testicular malignancies are an uncommon, life-threatening condition, which require prompt treatment. The case of a 26-year-old healthy man is described, who reported a 6-month painful bilateral gynaecomastia associated with secondary hypogonadism. Normal circulating 17beta-oestradiol (E2) levels showed an enhanced response to human chorionic gonadotrophin (hCG) testing, which led to a reduced testosterone (T)/E2 ratio. Both clinical and hormonal findings normalized following surgical exeresis of a left testicular mass, which proved to be a Leydig cell tumour (LCT) at histology. This report underlines the importance of ultrasonographic evaluation of the testes, whenever breast enlargement occurs in a healthy man, despite unremarkable findings on testicular examination. In addition, our case demonstrates that normal unstimulated circulating E2 levels do not allow the presence of a stromal testicular tumour to be ruled out and that the response of restored T levels to hCG testing can remain blunted up to 1 year after surgery. Finally, we claim that T/E2 ratio may be a useful tool in evaluating derangement of the endocrine milieu secondary to LCT.