What is gynecomastia?

A 15-year-old boy presents with history of breast enlargement noticed for the past 3 years. It was initially painful for the first 6 months and subsequently, the pain subsided. At this point, he was evaluated by a pediatrician in his annual school health examination, who noticed small testes in addition to gynecomastia. He was then referred to an endocrinologist for further evaluation, where the boy and his parents give the following clinical history. His birth weight was 3 kg. He was born after a term pregnancy by normal vaginal delivery and had a birth weight of 3 kg. Subsequent postnatal history did not include any neonatal seizures or prolonged neonatal jaundice. Subsequent development was age appropriate. He did not experience any episodes of seizures, or prolonged neonatal jaundice. There was no history of any chronic disease, central nervous system trauma, infections or irradiation. There is no history of abdominal or scrotal trauma, surgery or irradiation. He also did not receive any chemotherapy in the past. He does not give any history suggestive of orchitis or other scrotal infections. There is also no history of anosmia. His mother, however, complains of below par scholastic performance with average to poor grades. There is no consanguinity, family history of gyneco-mastia, delayed puberty, anosmia or infertility. Pubertal development was noticed at about 12 years of age. He has one sister who has had normal pubertal development.

On examination, the child has a height of 176 cm and weight of 65 kg. Mid-parental height is 166 cm. Arm span is 184 cm and upper to lower segment ratio was 0.83, which is suggestive of eunuchoid proportions. He has sparse facial hair. Axillary (Tanner Stage 2) and pubic hair (Tanner Stage 3) are sparse but present. Stretched penile length is 7.8 cm and bilaterally testes are palpable, small and firm, with a volume of 5 mL. He does not have goiter. His pulse is 74 per minute, blood pressure is 118/60 mm Hg, and respiratory rate is 18. He has a nontender gynecomastia with 5 cm of palpable tissue on the right and 3 cm on the left. His abdomen is soft with no palpable masses and other systems are also normal. No anosmia is appreciated on examination. Biochemical testing reveals normal thyroid, liver and renal functions. Elevated levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at 22 mIU/mL (normal 1.4–12) and 53 mIU/mL (normal 0.6–15 mIU/mL) respectively are discovered, with a low testosterone of 14 ng/dL (normal 350–850 ng/dL). A karyotype is ordered, and is 47XXY, which confirms Klinefelter’s syndrome. A detailed evaluation by a psychologist reveals some impulsivity and a normal Intelligence Quotient (IQ).

What is gynecomastia?