Superficial thrombophlebitis is the medical term for inflammation of superficial leg veins that are located just under the skin. It is caused by a small blood clot that forms in a vein and causes inflammation of the vein wall and typically occurs in people with varicose veins.
Risk factors for superficial thrombophlebitis include varicose veins, DVT and immobility. Symptoms usually include swelling, redness, and tenderness. An important consequence of thrombophlebitis is a risk of DVT, especially higher up the leg where superficial and deep veins meet.
Cho KH. Inflammatory Nodules of the Leg. Ann Dermatol. Nov 2012; 24(4): 383–392. doi: 10.5021/ad.2012.24.4.383
The figure shows inflammation of superficial leg veins—thrombophlebitis.