Gynecomastia (American English) or gynaecomastia (British
English) is the development of abnormally large breasts on males.
The term comes from the Greek gyne meaning "woman" and mastos
meaning "breast". The condition can occur physiologically in
neonates, in adolescents, and in the elderly. In adolescent boys
the condition is often a source of distress, but for the large
majority of boys whose pubertal gynecomastia is not due to obesity,
the breast development shrinks or disappears within a couple of
years.
The causes of common gynecomastia remain uncertain, although it has
generally been attributed to an imbalance of sex hormones or the
tissue responsiveness to them; a root cause is rarely determined
for individual cases. Breast prominence can result from hypertrophy
of either breast tissue or pectoral adipose tissue, and often a
combination of the two. Breast prominence due solely to excessive
adipose is often termed pseudogynecomastia
Physiologic gynecomastia occurs in neonates, at puberty and with
aging.
Potential pathologic causes of gynecomastia are: medications
including hormones, increased serum estrogen, decreased
testosterone production, androgen receptor defects, chronic kidney
disease, chronic liver disease, HIV, and other chronic illness.
Gynecomastia as a result of spinal cord injury and refeeding after
starvation has been reported. In 25% of cases, the cause of the
gynecomastia is not known.
