Answer:
The extent of the workup for gynecomastia depends on the age of onset. With the normal pubertal growth spurt during male adolescence, many boys undergo a small amount of breast hypertrophy. The incidence is approximately 30-40%, most occurs at around the age of 14, usually is asymmetric, frequently is tender and occasionally is unilateral for a portion of its course. Ordinarily the condition is self-limited and resolves in 6 to 18 months. The treatment is reassurance. A recent study (Clin Pediatr 1998 Jun;37(6):367-71) evaluated 60 boys with marked breast development (greater than 4cm) and found an endocrine abnormality in 7 patients and underlying medical problems in another 8 patients. The authors recommend an endocrine evaluation in all patients with marked pubertal gynecomastia.
Clinically significant gynecomastia in the prepubertal patient is worrisome. Excessive estrogen production or deficient testosterone production are the most likely causes. Excessive estrogen can result from either true hermaphroditism or testicular tumors (chorioepithelioma, interstitial cell tumor, Sertoli cell tumor, teratoma). Deficient testosterone production is usually caused by Klinefelter syndrome (XXY karyotype or an XXY/XY mosaic). In addition to experiencing gynecomastia, these patients are usually tall, have decreased facial and axillary hair and decreased testicular diameter and penile length. The risk of breast cancer is 20 times that of normal men. Other causes of deficient testosterone production include congenital adrenal hyperplasia, hyperthyroidism, and feminizing adrenal tumors. Prepubertal patients with gynecomastia should be referred to a pediatric endocrinologist for evaluation.
Breast enlargement in adults is usually due to excessive fat deposition or a combination of fat and glandular tissue. Like the gynecomastia of adolescence, it occurs in otherwise healthy men. Abnormal liver function secondary to liver disease and mild cirrhosis as well as drug therapy (see below) have been implicated. Routine endocrine screening has been advovated by some, but does not appear to be cost effective and is rarely productive (Am J Surg 1998 Dec;176(6):638-41).