A Case of Gynecomastia Caused by Amitriptyline Hydrochloride

Abstract

  A 79-year-old man who presented with a persistent allodynia of the left face and had been diagnosed as having postherpetic neuralgia underwent a stellate ganglion block and drug therapy. The patient had a history of alcoholic hepatitis and hepatic dysfunction. The patient complained of bilateral chest lumps after the oral administration of 10 mg/day of amitriptyline hydrochloride for 9 months. Two 40 mm×40 mm swollen areas were observed, one beneath each nipple, and CT images showed two enlargements of the mammary tissue, each 15 mm×35 mm in size, with one on each side. The patient was diagnosed as having gynecomastia, and the amitriptyline hydrochloride was immediately discontinued. The gynecomastia disappeared 6 months after the discontinuation of the oral medication.

  Gynecomastia is the benign proliferation of glandular breast tissue in men and can occur physiologically or as a disease symptom. In both cases, it occurs when female hormones become absolutely and/or relatively dominant over male hormones. The secretion of prolactin, a hormone that regulates mammary gland differentiation and development, is regulated by prolactin inhibiting and prolactin releasing factor (PRF). Tricyclic antidepressants can increase the relative amount of PRF, which can in turn accelerate prolactin secretion. Estrogen, a female hormone, is metabolized by conjugation in the liver, but this patient had a history of alcoholic hepatitis and impaired liver function. Aging can also cause breast enlargement. During old age, the synthesis of androgen is decreased, and the activity of aromatase, which is an enzyme that biosynthesizes estrogen from androgens, is increased. In this case, the combination of aging, liver dysfunction, and the use of amitriptyline hydrochloride may have caused a relative dominance of female hormones, resulting in gynecomastia.