A 17-year-old girl presents with primary amenorrhea, Tanner Stage 3 breast development, normal pubic and axillary hair, and a vaginal length of 6 cm on examination. Karyotype is 46,XY. Serum testosterone is in the male range. What is the most likely diagnosis?

• A Congenital adrenal hyperplasia (21-hydroxylase deficiency)
• B Müllerian agenesis (MRKH syndrome)
• C 5-alpha reductase deficiency
• D Complete androgen insensitivity syndrome (CAIS) ✓

Explanation

Complete androgen insensitivity syndrome (CAIS, 46,XY, non-functional androgen receptor) presents with female phenotype, absent uterus and fallopian tubes (MIF from testes is functional), Tanner III-IV breast development from peripheral oestrogen conversion, sparse or absent pubic/axillary hair (androgen-dependent), blind-ending vaginal pouch, and male-range testosterone. MRKH presents with 46,XX karyotype and normal testosterone. 5-alpha reductase deficiency presents with ambiguous genitalia in childhood, virilising at puberty.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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