Most Common Cause of Gynecomastia

Physiologic gynecomastia is the most common cause of gynecomastia, occurring in up to 57% of men due to normal hormonal fluctuations. 1

Pathophysiology

Gynecomastia results from a hormonal imbalance between estrogens and androgens, leading to proliferation of glandular breast tissue 2
The condition presents as a soft, rubbery, or firm mobile mass directly under the nipple, often painful when present for less than 6 months 3
Gynecomastia is bilateral in approximately 50% of patients 3

Neonatal period: Due to maternal estrogens 4
Puberty: Transient relative imbalances between androgens and estrogens during development 5
- Pubertal gynecomastia is self-limited in 75-90% of adolescents and typically regresses over 1-3 years 5
Aging: Hormonal changes in older men 4

Hormonal disorders:
- Hyperprolactinemia 6
- Hypogonadism (primary or secondary) 7
- Thyroid dysfunction 6
Systemic diseases:
- Liver cirrhosis 6
- Renal insufficiency 4
Genetic conditions:
- Klinefelter syndrome (significantly increases risk with a relative risk of 24.7) 6
Medications and substances:
- Antiandrogens 3
- Chemotherapeutic agents 6
- Various other medications 3
Obesity:
- Contributes to pseudogynecomastia but can also increase true gynecomastia through peripheral conversion of androgens to estrogens 6
Tumors (rare):
- Adrenal tumors that secrete estrogen 6
- Testicular tumors 7

Clinical evaluation should focus on:
- Differentiating true gynecomastia from pseudogynecomastia (fatty tissue deposition rather than glandular tissue enlargement) 3
- Evaluating medication history and temporal relationship between medication initiation and onset of gynecomastia 6
- Assessing for underlying medical conditions 6
Physical examination should include:
- Body habitus assessment and BMI calculation 3
- Evaluation of virilization status by examining body hair patterns 3
- Complete testicular examination 3
- Assessment of prostate size and morphology 3
- Visual field examination to detect signs of pituitary disorders 3

Most cases of physiologic gynecomastia resolve spontaneously and require no treatment 1
For persistent, painful gynecomastia:
- Patients with elevated baseline estradiol measurements should be referred to an endocrinologist 3
- Estrogen receptor modulators may be considered for testosterone deficient patients 3
- Surgical correction may be needed for cosmetic reasons or long-standing cases that have become fibrotic 3

Failing to distinguish between true gynecomastia and pseudogynecomastia, especially in obese patients 6
Ordering unnecessary imaging in clear cases of gynecomastia, which can lead to additional unnecessary benign biopsies 3
Overlooking medication-induced causes, which are frequent contributors to breast enlargement 7
Delaying treatment in cases causing significant psychological distress, particularly among adolescents 1