Congenital Aromatase Deficiency in an Adult Male: A Case Report of Clinical Course and Symptom Reversal with Estrogen Supplementation

Congenital aromatase deficiency is an autosomal recessive CYP19A1 loss-of-function disorder that blocks conversion of androgens to estrogens. A man with homozygous CYP19A1 c.628G>A (exon 5) presented with longstanding fatigue, low libido, and desire to maintain fertility. Physiologic estrogen replacement was started with transdermal estradiol 0.0375 mg. After three months of estrogen therapy, the patient reported markedly improved energy and libido. Follow-up evaluation showed a rise in serum estradiol with normalization of gonadotropins, while maintaining spermatogenesis. This case illustrates the essential role of estrogen in male physiology, sexual function, and fertility. Estradiol replacement can alleviate hypoestrogenic symptoms with preservation of spermatogenesis. • Male aromatase deficiency can cause fatigue and low libido. • Low dose estradiol restored pituitary feedback and improved fatigue and libido. • Spermatogenesis persisted during estradiol therapy with serial semen monitoring. • Estrogen is a key regulator of male sexual function and pituitary gonadotropin control.