A 15-year-old girl has never had a menstrual period. She has normal secondary sexual characteristics. Examination reveals a blind-ending vagina with absent uterus. Karyotype is 46,XY. The most likely diagnosis is:

• A Turner syndrome (45,X0)
• B Mayer-Rokitansky-Küster-Hauser syndrome — 46,XX with uterovaginal aplasia
• C Swyer syndrome (46,XY pure gonadal dysgenesis)
• D Complete androgen insensitivity syndrome (CAIS) — androgen receptor mutation, 46,XY ✓

Explanation

Complete Androgen Insensitivity Syndrome (CAIS) presents with 46,XY karyotype, normal female external appearance, normal breast development (from peripheral aromatization of testosterone), absent or sparse pubic/axillary hair, blind-ending vaginal pouch, absent uterus (as testes produce AMH), and primary amenorrhea. Swyer syndrome also has 46,XY but presents with infantile (undeveloped) external genitalia and streak gonads. MRKH syndrome has 46,XX, normal secondary characteristics but absent uterus. Gonads in CAIS carry malignancy risk and are removed after puberty.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.