Cystic adventitial disease of the popliteal vein and artery in siblings

Cystic adventitial disease (CAD) is an uncommon condition in which mucoid cysts form within the adventitial layer of the arterial or venous wall. We have presented two cases in which two first-degree relatives (brother and sister) had acquired CAD ∼6 years apart, one involving the popliteal artery and the other involving the popliteal vein. We have reported a rare case of a possible familial association of CAD. We have discussed the etiology, diagnostic criteria, and imaging modalities between arterial and venous CAD to aid in the management and selection of optimal treatment strategies.