Giant ulnar artery aneurysm secondary to congenital arteriovenous fistula and trauma: a case report.

An 80-year-old woman presented with a giant ulnar artery aneurysm that had developed secondary to a congenital arteriovenous fistula and trauma. The aneurysm progressively enlarged over 33 years, reaching 68 × 88 mm with a forearm circumference of 31 cm. Despite proximal ulnar artery ligation performed three years prior, the aneurysm continued to enlarge due to collateral circulation arising from a tortuous segment of the brachial artery. Definitive surgical intervention was undertaken, comprising collateral vessel ligation, brachial artery reconstruction, and endoaneurysmorrhaphy with removal of 235 g of organized thrombus. Histopathological examination revealed transmural sclerosis consistent with an atherosclerotic aneurysm. Preoperative ultrasound mapping of neurovascular structures facilitated safe dissection in the setting of distorted anatomy. Postoperatively, forearm circumference improved to 25 cm. Residual aneurysm perfusion was identified on contrast-enhanced computed tomography, highlighting the technical complexity of achieving complete exclusion in giant aneurysms with multiple inflow sources.