Introduction
Premature pubarche (PP) is defined as the appearance of pubic hair before 8 yr of
age in
girls and 9 yr in boys, without other signs of puberty. The appearance of pubarche
before
one year of life is rare, with few reports in the literature. We present a case of
PP in a
7-mo-old infant that was found to be in mini-puberty and also had non-classical congenital
adrenal hyperplasia (CAH).
Case Report
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
Fig. 1.
A: Pubic hair confined to the scrotum. B: Six months later, pubic hair resolved.
). 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), alpha-fetoprotein (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.
Discussion
As noted, PP is defined as the appearance of pubic hair before 8 yr of age in girls
and 9
yr in boys, without other signs of puberty. It more frequently occurs between the
ages of 6
to 8 yr, with a clear predominance in girls (1).
Pubarche in the first year of life is rare, with few reports and little description
in the
literature. It is thought to be benign because most cases resolve spontaneously; however,
long-term follow-up is necessary to determine the etiology. When clinical signs of
pubarche
are noted, careful physical examination and analysis of the growth chart should be
performed. The initial biochemical evaluation must include the determination of sex
steroids
and 17-OH-progesterone levels. If testosterone concentrations are elevated, βhCG and
an
abdominal and pelvic ultrasound should be evaluated (2). The diagnosis of premature
pubarche is based on the exclusion of other causes of
prepubertal hyperandrogenism (3), and the etiology in
infants remains unknown. A possible explanation might be the early physiological rise
of
testosterone in mini-puberty (4), which is not
accompanied by other signs of secondary sexual development (axillary hair or odor,
advanced
bone age, and/or acceleration of the growth rate) and resolves spontaneously. Among
the
pathological causes that may initially present as premature pubarche, classic or
non-classical CAH, precocious puberty, virilizing tumors, and exogenous exposure must
be
excluded. Classically, these conditions present with other findings such as clitoromegaly,
increased penile length, advanced bone age, and growth acceleration. Despite the fact
that
this case did not present with other clinical findings of CAH, elevated 17-OH-progesterone
concentration suggested non-classical CAH. Molecular study showed a homozygous variant
of
p.Val281Leu. This pathogenic variant has been described in patients with non-classical
CAH
(5); however, to our knowledge, this variant has not
been described in infants that present with premature pubarche. As this boy’s phenotype
resolved in time and did not present other features of CAH, the clinical significance
of
this genotype is not clear.
Treatment is not always indicated in patients with non-classical CAH, unless they
are
symptomatic. Symptomatic hyperandrogenism can be reduced with low-dose glucocorticoids,
as
in children with early onset and rapid progression of pubic and body hair, rapid growth,
and/or skeletal advancement.
Conflict of Interest: The authors have no relevant conflict of interest.