Underrecognized Thrombotic Risk in Klinefelter Syndrome: A Clinical Insight.

Klinefelter syndrome (KS), the most common male aneuploidy (47,XXY), is linked to hypogonadism, gynecomastia, and infertility, with an established but underrecognized association with venous thromboembolism and limited data on mechanisms in patients without additional thrombophilic conditions. We report the case of a 33-year-old South Asian male with subacute-to-chronic deep vein thrombosis (DVT) of the right leg and absent traditional thrombosis risk factors. Clinical evaluation, hormonal assays, and karyotyping confirmed KS. Extensive investigations ruled out congenital and acquired thrombophilias. The patient responded well to anticoagulation therapy, achieving symptom resolution. This case highlights the need for awareness of thrombotic risks in KS and underscores the importance of further research into the underlying mechanisms of this association.