Oestrogen and progesterone receptors in men with bilateral or unilateral pubertal macromastia

Abnormalities at the tissue receptor level may be important in the pathophysiology of pubertal macromastia, which may be unilateral or bilateral. We studied breast tissue removed from seven boys of age 16-17 years, five with bilateral and two with unilateral gynaecomastia. We confirmed that their physical features, karyotype, and plasma concentrations of testosterone, oestradiol, LH, FSH, and prolactin were all normal for adolescent males. Oestrogen and progesterone receptors were measured with a steroid binding (dextran coated charcoal) assay which was used for breast cancer receptor studies. Oestrogen receptors were not detectable in any of the 12 breasts studied. Progesterone receptors were detectable at a low level in two patients with bilateral gynaecomastia, one breast from each patient. We conclude that although the development of bilateral or unilateral male macromastia in puberty may yet be mediated by a local tissue receptor abnormality, this disorder is probably not mediated by an abnormal increase in oestrogen receptor number.