[Persistant pubertal gynecomastia. Biological study (author's transl)].

17 cases of peristant pubertal gynecomastia (which differs from physiologic breast enlargement by their volume and duration) were studied. Plasma estrogens and urinary phenol steroids excretion were found higher than in normal boys. The main biological finding in these subjects was a decrease of the plasma testosterone/estradiol ratio, and a moderate but transient increase in plasma prolactin. LH and FSH were within the normal range. In the mammary tissue, no estrogen receptor was detectable and aromatase activity was in the same range as in adipose tissue. Pathological examination showed a simulataneous proliferation of galactophoric and fibroblastic stroma. Thus, persistant pubertal gynecomastia could be related to an elevated sensitivity of the mammary tissue to a moderate increase of plasma estrogens. Such a sensitivity could be due to an insufficient masculinization of the mammary anlage during the intra-uterine life.