Undiagnosed bilateral complete cervical rib with subclavian artery aneurysm presenting as acute ischaemic limb following high-altitude expedition.

Arterial thoracic outlet syndrome is relatively rare and often exclusively seen in the presence of bony anomalies. High-altitude (HA) travel is commonly associated with thrombosis; however, arterial thromboembolism is less frequently described. We describe a case of a young man with undiagnosed bilateral cervical rib, who went for an HA trek, subsequent to which developed acute limb ischaemia of right arm. Diagnostic workup revealed a subclavian artery aneurysm as well along with complete bony bilateral cervical ribs. Thoracic outlet syndrome should be kept as a differential diagnosis in a case of acute limb ischaemia in a healthy adult.