Estrogen (E2) and Progesterone receptors in gynecomastia

Most cases of gynecomastia are idiopathic but others are associated with disendocrinopathies or drugs. A subset of patients (Klinefelter's syndrome) carries an increased risk of malignant degeneration. Breast content of Estrogen (E2R) and Progesterone (PgR) receptors and breast cells flow cytometry could be potential indicators of the biological evolution of the lesions. Twenty-seven adult males (age 13-18 years) were studied. Eleven had bilateral gynecomastia. In all patients E2R expression was very low, ranging from 1 to 10 fmol/mg cytosol protein. PgR expression was somewhat higher in a few cases of idiopathic gynecomastia with values up to 44 fmol/mg cytosol protein. Two of the three cases of Klinefelter's syndrome had very high PgR levels. PgR expression differed in some cases of idiopathic bilateral gynecomastia from one breast to the contralateral, thus suggesting autonomous breast self regulation. Aneuploidy was found in breast tissue of Klinefelter's patients and in five cases of idiopathic gynecomastia. Fibroblasts or mammary gland cells could express the high PgR levels. This overexpression of PgR and the changes in ploidy may have predictive meaning in the evolution of the lesions.