Virilization of the 46,XX infant may be attributed to maternal or fetoplacental origin. Maternal sources may be endogenous, as with an
androgen-producing
tumor, or
drug-related. Iatrogenic
virilization by maternal
drug exposure is rarely reported, with individual case reports and case series demonstrating the effects of
progesterone and other medications affecting the pituitary-ovarian axis.1-3 The class of medications known as
aromatase inhibitors are recognized as effective in treating
hormone receptor-positive
breast cancer by preventing the conversion of
androgens into
estrogens by
aromatase. In fetal development, placental
aromatase plays a critical role in preventing
virilization of the XX fetus by maternal and fetal
androgens during development. In the setting of placental
aromatase deficiency, the XX fetus may be virilized. It is conceivable, therefore, that maternal exposure to
aromatase inhibitors early in gestation may lead to in utero
virilization, though there have been no known reports of this phenomenon to date. We present a case of
virilization of a 46,XX infant attributed to pharmacologic
aromatase inhibition. The infant's parents provided informed consent for the reporting of this case.