The role of expression of estrogen and progesterone receptors in idiopathic gynecomastia etiology

Role of ERα and Aromatase in Juvenile Gigantomastia

CONTEXT

Approximately 150 patients with juvenile gigantomastia have been reported in the literature but the underlying biologic mechanisms remain unknown.

OBJECTIVE

To conduct extensive clinical, biochemical, immunochemical, and genetic studies in 3 patients with juvenile gigantomastia to determine causative biologic factors.

METHODS

We examined clinical effects of estrogen by blockading estrogen synthesis or its action. Breast tissue aromatase expression and activity were quantitated in 1 patient and 5 controls. Other biochemical markers, including estrogen receptor α (ERα), cyclin D1 and E, p-RB, p-MAPK, p-AKT, BCL-2, EGF-R, IGF-IR β, and p-EGFR were assayed by Western blot. Immunohistochemical analyses for aromatase, ERα and β, PgR, Ki67, sulfotransferase, estrone sulfatase, and 17βHD were performed in all 3 patients. The entire genomes of the mother, father, and patient in the 3 families were sequenced.

RESULTS

Blockade of estrogen synthesis or action in patients resulted in demonstrable clinical effects. Biochemical studies on fresh frozen tissue revealed no differences between patients and controls, presumably due to tissue dilution from the large proportion of stroma. However, immunohistochemical analysis of ductal breast cells in the 3 patients revealed a high percent of ERα (64.1% ± 7.8% vs reference women 9.6%, range 2.3-15%); aromatase score of 4 (76%-100% of cells positive vs 30.4% ± 5.6%); PgR (69.5% ± 15.2% vs 6.0%, range 2.7%-11.9%) and Ki67 (23.7% ± 0.54% vs 4.2%). Genetic studies were inconclusive although some intriguing variants were identified.

CONCLUSION

The data implicate an important biologic role for ERα to increase tissue sensitivity to estrogen and aromatase to enhance local tissue production as biologic factors involved in juvenile gigantomastia.

The role of steroid receptors, peptides and growth factors in the aetiopathogenesis of idiopathic gynecomastia

Idiopathic gynecomastia is a diagnosis of exclusion. We aimed to evaluate the role of steroids, peptides and growth factors in these patients. Those with bilateral idiopathic gynecomastia (n = 29) (Simon's grade IIb or III) who underwent gland excision were evaluated by immunohistochemical techniques using semi-quantitative grading for oestrogen receptor (ER), progesterone receptor (PR), aromatase, androgen receptor (AR), peptides (IGF-1, IGF-2, HER-2, parathyroid-hormone related peptide [PTHrP]) and growth factors (EGFR, TGFβ). The cohort comprised 29 patients, with a mean age of 25.3 ± 5.1 years and a mean body mass index of 27.2 ± 2.3 kg/m² . Grade IIb gynecomastia was present in 79.1% and moderate-to-severe insulin resistance (HOMA-IR >3) in 53.7% of patients. ER expression was positive in 100% samples, followed by AR (96.5%), aromatase (96.5%) and PR (93.1%). IGF-1 was expressed in 86.2% of the cohort, IGF2 in 27.5% and HER-2 in only two samples, with both showing weak immunoexpression. None of the patients had positive expression of EGFR, TGF-β or PTHrP. There was no association between immunoexpression and gynecomastia grade. This study demonstrates the predominant role of oestrogen, aromatase and insulin resistance in the aetiopathogenesis of idiopathic gynecomastia and implicates the paracrine hyperestrogenic milieu in its causation as circulating hormones were normal.

Biochemical features of eugonadal patients with idiopathic gynaecomastia: A retrospective cross-sectional study

Patients with idiopathic gynaecomastia have greater BMI and an unfavourable lipid profile compared with age-matched controls. Twenty-five adult eugonadal patients with idiopathic gynaecomastia and 50 age- and BMI-matched controls were selected. Clinical and biochemical parameters and ultrasound testis volume were reviewed retrospectively. Patients and controls differed for no biochemical parameter, except for LH levels, which were 31% higher in patients (p = 0.019), although within the normal range. Compared with controls, patients had a threefold greater rate of elevated LDL-c (p = 0.025). Patients ≥ 25 years had higher levels of serum LDL-c compared with either patients < 25 years (p = 0.006) or controls ≥ 25 years (p = 0.012). In patients, both at bivariate analysis and at linear regression, age correlated positively with total cholesterol and LDL-c, the latter correlated inversely with total testosterone. Negative interactions were found for age and total testosterone with LDL-c, for LH and estradiol to testosterone ratio (E2:T) with LDL-c, and for age and E2:T with total cholesterol. Our data suggest inadequate local androgen action in patients with idiopathic gynaecomastia. This partial androgen resistance might blunt the beneficial effects of testosterone on lipid metabolism. Further studies are needed to verify whether this metabolic derangement impacts the cardiovascular health of these patients.