[How I explore ... an enlarged red leg]

A consultation motivated by an enlarged red leg is a common situation. The causes are multiple and the diagnosis primarily relies on case history and physical examination distinguishing inflammatory red legs from erythemato-violaceous presentations. Additional diagnostic search cannot be described as a single standardized procedure. Each disease calls for specific and different paraclinical investigations. The most frequent cause is erysipelas or a thrombophlebitis. Some vascular malformations and some functional circulatory disturbances are also possible, as well as sequelae of panniculitis or borreliosis.