Condition	Characteristics
Medication or illicit drug use	Discrete, round, mobile mass under the areola, usually bilateral; common agents include spironolactone, anabolic steroids, antipsychotics (e.g., haloperidol), and illicit drugs, including marijuana, heroin, and amphetamines
Physiologic gynecomastia	Proliferation of glandular breast tissue; palpable firm or rubbery breast tissue that is concentric to the nipple or areola; typically bilateral but may be unilateral; most common form of gynecomastia; occurs in newborns, adolescents, and men older than 50 years
Primary hypogonadism	Increased glandular breast tissue concentric to the nipple; usually bilateral; elevated luteinizing hormone level and diminished testosterone level
Pseudogynecomastia	Increased adipose tissue in the breasts, rather than glandular tissue; occurs in patients who are obese
Testicular cancer	Leydig cell and Sertoli cell tumors can produce estrogen, resulting in gynecomastia; testicular mass may be palpable, and human chorionic gonadotropin levels may be elevated