Erythema nodosum is a disorder including formation of characteristic painful, red skin nodules .
Causes, incidence, and risk factors
Erythema nodosum is characterized by tender, reddened nodules , usually on the front of the legs. It is more common in women. The exact cause of the nodules is unknown. Some cases may be associated with infections such as streptococcus, coccidioidomycosis , fungal infections, tuberculosis , Hepatitis B , syphilis , cat-scratch disease, tularemia , Yersinia infection, leptospirosis , psittacosis , histoplasmosis , coccidioidomycosis, and mononucleosis ( EBV ). Sensitivity to drugs such as oral contraceptives, penicillin, sulfonamides, sulfones, barbiturates, hydantoin, phenacetin, salicylates, iodides, or progestin may be associated with other cases. Other associated disorders include leukemia , sarcoidosis, rheumatic fever , and ulcerative colitis . Erythema nodosum characteristically appears on the shins, although it may occur on other areas of the body (buttocks, calves, ankles, thighs and upper extremities). The lesions begin as flat, but firm hot red painful lumps (approximately an inch across). Within a few days they may become purplish then over several weeks fade to a brownish flat patch . Systemic findings may include fever and malaise .
Signs and tests
The diagnosis is primarily based on the appearance of the skin nodules . Biopsy of a nodule may show characteristic changes (septal panniculitis).
Treatment
The underlying infection, drug, or disease should be identified and treated. Nonsteroidal anti-inflammatory medications (NSAIDs) may reduce symptoms. Occasionally, an oral potassium iodide (SSKI) solution may produce prompt resolution of the nodules . Corticosteroids or salicylate medications may be needed to reduce acute inflammation. Analgesics and limitation of activity may be needed to control varying amounts of pain. Topical therapy is not generally needed, although hot or cold compresses may reduce discomfort.
Expectations (prognosis)
Erythema nodosum is uncomfortable, but not usually dangerous to the health. Symptoms usually disappear within about 6 weeks, but may recur.
Calling your health care provider
Call for an appointment with your health care provider if symptoms of erythema nodosum develop.