Presence of spermatogonia in 47,XXY men with no spermatozoa recovered after testicular sperm extraction.

Objective: To evaluate the presence of spermatogonia in men diagnosed with Klinefelter syndrome (KS), in whom no testicular spermatozoa were recovered by testicular sperm extraction.

Design: Retrospective case series.

Setting: University hospital.

Patient(s): Testicular samples from 22 nonmosaic 47,XXY men, aged 24-43 years, with no spermatozoa at multiple biopsies.

Intervention(s): Paraffin-embedded testicular tissue was sectioned and stained with hematoxylin-eosin, and immunostainings were performed for both MAGE-A4 and vimentin.

Main Outcome Measure(s): The presence of spermatogonia.

Result(s): Massive fibrosis and hyalinization were observed in all men with KS. Spermatogonia were observed in 4 of 22 men with KS, with differentiation up to the spermatocyte level in 2 of them.

Conclusion(s): A few men with KS, having no spermatozoa after testicular sperm extraction, still had few spermatogonia. These patients may eventually benefit from in vitro maturation using spermatogonial stem cells. The adult KS population can thus be divided into three subgroups: one subgroup showing focal spermatogenesis, a second having spermatogonia, and a third group in which no germ cells can be recovered. Further research is necessary to unravel the mechanism leading to these different patterns in patients with KS.