A 16-year-old girl is concerned about not having started her menstrual cycles. She has normal secondary sexual characteristics (Tanner stage IV breasts and pubic hair). Pelvic exam and ultrasound show absent uterus. Karyotype is 46,XY. The most likely diagnosis is:

• A Turner syndrome
• B Müllerian agenesis (Mayer-Rokitansky-Küster-Hauser syndrome)
• C 5-alpha reductase deficiency
• D Complete androgen insensitivity syndrome (CAIS) ✓

Explanation

Complete androgen insensitivity syndrome (CAIS) presents with 46,XY karyotype, phenotypically female appearance with normal breast development (estrogen from peripheral conversion of androgens), absent or sparse pubic and axillary hair, absent uterus (Müllerian structures absent due to normal AMH from testes), and primary amenorrhea. Müllerian agenesis (MRKH) has 46,XX karyotype with absent uterus/vagina but normal ovaries and pubic hair. Turner syndrome has 45,X with streak gonads and short stature. 5-alpha reductase deficiency presents with ambiguous genitalia at birth in 46,XY individuals.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.