Adolescent Development, testicular feminization
Most teens have menarche within 2 to 2.5
years after thelarche
or within 1 year of attaining full physical maturity. The presence of
primary amenorrhea and normal secondary sexual characteristics at age 17 in the
otherwise healthy adolescent girl described in the vignette
warrant further evaluation.
There are numerous causes of primary amenorrhea, but not all need to be
considered in a patient who has mature secondary sexual characteristics.
Although her external genitalia are
phenotypically
female, the presence of a blind vaginal pouch is most consistent with the
diagnosis of male
pseudohermaphroditism. A serum
karyotype
will confirm this diagnosis.
Complete testicular feminization is the
most common cause of male
pseudohermaphroditism (phenotypic
female who has 46,XY karyotype
and with testes) and results from androgen insensitivity. Not all
affected individuals present with ambiguous genitalia because the spectrum of
sensitivity is broad. If the receptor to androgens is nonfunctional or absent,
the external genitalia will be those of a normal female. The diagnosis is
usually delayed until the absence of menses brings the adolescent to medical
attention. Internal female genitalia do
not form because the müllerian
ducts regress under the effects of
müllerian
inhibiting factor produced by occult male gonads located in the abdomen.
However, low levels of gonadal
and adrenal estrogens, unopposed by androgens, allow breast development to occur
in affected individuals.
Signs and symptoms of male pseudohermaphroditism are variable, depending on the
etiology. As described previously, the phenotypic female may
present with primary amenorrhea or an infant may have ambiguous genitalia noted
at birth. The otherwise healthy teenager who has androgen insensitivity
may have sparse
axillary
and pubic hair, normal breast development, and a blind vaginal pouch with
absence of the ovaries, uterus, and fallopian tubes. Testes and normal male
levels of testosterone are present.
Because the adolescent described in the vignette does not have a central cause
of amenorrhea, computed tomography of the head is unnecessary. Furthermore,
magnetic resonance imaging is the study of choice to visualize the pituitary
gland. Computed tomography of the pelvis may confirm the absence of internal female genitalia, but
will not make the diagnosis. A serum estradiol level is unnecessary in the
adolescent who has mature breast development. A serum prolactin level is also
not indicated because the primary amenorrhea clearly stems from abnormal genital
anatomy.
References:
Anhalt H, Neely EK, Hintz RL. Ambiguous genitalia. Pediatr Rev. 1996;17:213-220
Neinstein LS. Amenorrhea. In: Adolescent Health Care: A Practical
Guide. 3rd ed. Baltimore, Md: Williams & Wilkins; 1996:783-795
Rapaport R. Hermaphroditism (intersexuality). In: Behrman RE, Kliegman
RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 16th ed.
Philadelphia, Pa: WB Saunders Co; 2000:1760-1767