Premature pubarche in an infant: nonclassical congenital adrenal hyperplasia or mini-puberty variant?

A previously healthy, 7-mo-old male infant presented with a 3-mo history of pubic hair. He was a healthy, term newborn who was born to nonconsanguineous parents, and had appropriate weight and length. Physical examination revealed thick and long pubic hair on the scrotum, without hyperpigmentation or enlargement of the penis (Fig. 1a). No other signs of virilization or secondary sexual development were noted. His height (–0.08 SDS) and weight (–0.11 SDS) were normal for his age and appropriate for midparental height, with no apparent acceleration in growth rate. Laboratory data obtained the same day showed normal dehydroepiandrosterone sulfate (DHEA-S) and androstenedione levels, as well as negative results for β-subunit of human chorionic gonadotropin (βhCG), alphafetoprotein (AFP), and carcinoembryonic antigen (CEA). Basal plasma LH concentration was 1.5 mIU/ml (Reference value [RV]: 0.02–0.3 mIU/ml), testosterone was 25.2 ng/dl (RV: < 2.5 ng/dl), and 17-OH-progesterone was 2.48 ng/ml (RV: < 1.1 ng/ml) (gas chromatography/mass spectrometry). Bone age was equal to his chronological age. Abdominal ultrasound did not show any masses, and demonstrated normal adrenal glands. Due to his elevated 17-OH-progesterone concentration, analysis of the CYP21A2 gene was performed and showed a homozygous variant of p.Val281Leu. Genetic studies of the parents were not done. After an observation period of 6 months, pubarche spontaneously resolved (Fig. 1b), with no other signs of virilization, and growth velocity remained normal.