[Prepubertal gynecomastia at the debut of hereditary tumors predisposition syndrome (clinical case reports)].

Peutz-Jeghers Syndrome (Peutz-Jeghers Syndrome, PJS) refers to syndromes of hereditary tumor predisposition and is caused by pathological variants of the STK11 gene, leading to a defect in the synthesis of serine/threonine kinase 11 protein, which acts as a tumor suppressor.Clinical symptoms of the syndrome are combination of hamartomatous polyposis of the gastrointestinal tract and specific skin-mucosal hyperpigmentation. Also, this disease is characterized by a high risk of developing gastrointestinal and extra-intestinal tumors, including benign or malignant tumors of the reproductive system.One of the first signs of the disease in male patients may be prepubertal gynecomastia associated with large-cell calcifying Sertoli cells tumors expressing aromatase. In contrast to from pubertal gynecomastia, prepubertal is extremely rare, and it is often based on pathological causes. Early diagnosis of patients with pre-pubertal gynecomastia, including Peitz-Jaegers syndrome, defines the tactics of gynecomastia management and protocols for monitoring the development of other components of the disease in the future.This article describes two patients with pre-pubertal gynecomastia and Peitz-Jaegers syndrome with different molecular genetic defects: in one case associated with duplication of the STK11 gene site, in the other - with microdeletion of the short arm of chromosome 19 containing this gene.