A 22-year-old woman has primary amenorrhoea. She has normal secondary sexual characteristics (Tanner Stage 5 breast development, pubic and axillary hair present) but no uterus on ultrasound. Karyotype is 46,XY. Serum testosterone is in the male range. What is the diagnosis?
- A Müllerian agenesis (MRKH syndrome)
- B Swyer syndrome (46,XY pure gonadal dysgenesis)
- C Complete androgen insensitivity syndrome (CAIS) ✓
- D 5-alpha reductase deficiency
Explanation
Complete androgen insensitivity syndrome (CAIS) presents as 46,XY individual with male-range testosterone but complete resistance to androgen action — resulting in female external phenotype with excellent breast development, absent/scant pubic and axillary hair in classic CAIS (though mild cases may have normal hair), absent uterus and fallopian tubes (absent Müllerian structures due to normal AMH production), and blind-ending vagina. MRKH is 46,XX with no uterus and normal ovaries. Swyer syndrome has a uterus (streak gonads, no testosterone). 5-alpha reductase deficiency presents with ambiguous genitalia at birth, not primary amenorrhoea with Tanner 5 development.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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