Huge ovarian cyst in a neonate with classical 21-hydroxylase deficiency.

Congenital adrenal hyperplasia is the most common cause of ambiguous genitalia worldwide, with an incidence of 1 in 15,000 live births. The most frequently-occurring subtype, 21-hydroxylase deficiency, results in diminished production of aldosterone and cortisol as well as increased androgen secretion. Previous studies have reported a relationship between ovarian cyst formation and adrenal androgen excess; nevertheless, neonatal large ovarian cysts have rarely been reported in newborns with congenital adrenal hyperplasia. Herein, we present the unique case of a neonate with classical 21-hydroxylase deficiency who underwent surgery for a huge unilateral solitary ovarian follicular cyst on the seventh postnatal day. Possible mechanisms by which androgen excess may cause ovarian cyst formation are also discussed.