Erythema nodosum

Definition:

A group of symptoms 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 infection such as streptococcus infections, coccidioidomycosis, fungal infections, tuberculosis, hepatitis B, syphilis, cat-scratch disease, tularemia, Yersinia infection, leptospirosis, psittacosis, histoplasmosis, coccidioidomycosis, mononucleosis (EBV) infection, and sarcoidosis.

Sensitivity to drugs such as penicillin, sulfonamides, sulfones, barbiturates, hydantoin, phenacetin, salicylates, iodides, or progestin may be associated with other cases. Associated disorders include leukemia, sarcoidosis, rheumatic fever, and ulcerative colitis, miliary TB, and conditions such as pregnancy and use of oral contraceptives.

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 elevated hot red painful hard lumps approximately an inch across. Within a few days the become purplish then over several weeks fade to a brownish flat patch. Systemic findings may include fever and malaise.