Familial occurrence of Paget–Schroetter syndrome in biological brothers: a case report

Introduction and importance: Paget–Schroetter syndrome (PSS) is a rare venous subtype of thoracic outlet syndrome caused by subclavian vein compression and upper-extremity deep vein thrombosis. Repetitive overhead activity and anatomic compression are recognized risk factors. A targeted search found no prior peer-reviewed report of PSS in biological siblings, although familial clustering has been described in other forms of thoracic outlet syndrome. Case presentation: Two biological brothers developed PSS 4 years apart. A 17-year-old basketball player presented with right arm swelling, paresthesia, and axillary vein thrombosis extending into the basilic vein. He underwent catheter-directed thrombolysis, first rib resection, and anticoagulation with good functional recovery. His 18-year-old brother, a collegiate swimmer, presented with left arm swelling and shoulder pain. Family history prompted early imaging, which showed subclavian, axillary, and brachial vein thrombosis. He underwent thrombolysis, first rib resection, scalenectomy, thrombectomy, and anticoagulation, with a return to competitive swimming. Recurrent swelling at 6 months required balloon angioplasty. Thrombophilia testing was negative in the older brother, whereas the younger carried a heterozygous Factor V Leiden mutation. Clinical discussion: These cases may represent the first reported occurrence of PSS in biological siblings. Their clustering cannot distinguish between inherited susceptibility and shared anatomical, athletic, environmental, or coincidental factors. Heterozygous Factor V Leiden may increase thrombotic risk in the younger brother, but it does not explain disease occurrence in both cases. Conclusion: Both brothers had favorable outcomes after thrombolysis, anticoagulation, and surgical decompression. Recognition of a family history may facilitate earlier diagnosis in young athletes presenting with unilateral upper-extremity swelling.