A 24-year-old man is evaluated for infertility. He is tall with eunuchoid proportions, gynecomastia, and small firm testes. Semen analysis shows azoospermia. Serum testosterone is low with elevated LH and FSH. What is the most likely chromosomal complement?
- A 46,XY
- B 47,XYY
- C 47,XXY ✓
- D 45,X/46,XY mosaic
Correct answer: C. 47,XXY
Explanation
The picture is classic Klinefelter syndrome, the most common cause of primary testicular failure in males. Extra X material causes hyalinized seminiferous tubules, so FSH rises, while Leydig cell insufficiency lowers testosterone with compensatory high LH, driving the tall eunichoid habitus and gynecomastia. In 47,XYY males, testes are histologically normal and fertility is usually preserved, which eliminates the closest distractor.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.