Erythema nodosum leprosum is a skin condition caused by leprosy, which is characterized by tender, red nodules appearing on the legs, arms, and other parts of the body. The nodules are typically a symptom of a reaction to the bacteria that causes leprosy. There are a variety of synonyms that have been used to describe erythema nodosum leprosum, including type 2 lepra reaction, lepromatous erythema nodosum, leprosy nodules, and leprosy bumps. Despite the different names used to describe the condition, erythema nodosum leprosum is commonly recognized by its distinct symptoms and can be treated with a course of antibiotics.