A 16-year-old girl is evaluated for primary amenorrhoea. She has well-developed breasts (Tanner stage 4), very sparse pubic and axillary hair, and bilateral groin swellings. Ultrasound shows no uterus. Karyotype is 46,XY and serum testosterone is in the adult male range. What is the most likely diagnosis?

• A Complete androgen insensitivity syndrome ✓
• B Swyer syndrome (46,XY pure gonadal dysgenesis)
• C Mayer-Rokitansky-Kuster-Hauser syndrome
• D 5-alpha-reductase deficiency

Explanation

Androgen receptor defect means testosterone cannot act, so Wolffian structures and external male genitalia fail to develop while testicular AMH removes the uterus. Peripheral aromatization of testosterone produces breasts, and absence of androgen action gives scant pubic hair. Swyer syndrome is the killer distractor, but its streak gonads produce no testosterone or AMH, so breasts are absent and pubic hair is typically normal. Gonads here should be removed after puberty because of malignancy risk.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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