Adventitial cystic disease of the common femoral vein is a rare Decanters condition.We herein report the case of a 50-year-old woman who presented with painless swelling in her left lower leg that resembled deep vein 7 Piece Power Reclining Sectional thrombosis.She underwent femoral exploration and excision of the cystic wall.The presentation, investigation, treatment, and pathology of this condition are discussed with a literature review.