Inflammation of fat cells under skin, leading to sore red lumps, usually on both shins. Other uses: arthritis/arthralgia due to gout, vascular eczema/lung, functional disturbances.SkinEncyclopedia Entry for Erythema Nodosum :Erythema nodosum - seen in coccidioidomycosis (Coccidioides immitis)Encyclopedia Entry for Erythema Nodosum :Erythema nodosum leprosum - Mycobacterium lepraeEncyclopedia Entry for Erythema Nodosum :Erythema nodosum. In about half of cases, the exact cause of erythema nodosum is unknown. The remaining cases are associated with an infection or other systemic disorder. Some of the more common infections associated with the disorder are: Streptococcus (most common) Cat scratch disease Chlamydia Coccidioidomycosis Hepatitis B Histoplasmosis Leptospirosis Mononucleosis (EBV) Mycobacteria Mycoplasma Psittacosis Syphilis Tuberculosis Tularemia Yersinia Erythema nodosum may occur with sensitivity to certain medicines, including: Antibiotics, including amoxicillin and other penicillins Sulfonamides Sulfones Birth control pills Progestin Sometimes, erythema nodosum may occur during pregnancy. Other disorders linked to this condition include leukemia, lymphoma, sarcoidosis, rheumatic fever , Bechet disease, and ulcerative colitis. The condition is more common in women than it is in men.Erythema nodosum is most common on the front of the shins. It may also occur on other areas of the body such as buttocks, calves, ankles, thighs, and arms. The lesions begin as flat, firm, hot, red, painful lumps that are about 1 inch (2.5 centimeters) across. Within a few days, they may become purplish in color. Over several weeks, the lumps fade to a brownish, flat patch. Other symptoms may include: Fever General ill feeling (malaise) Joint aches Skin redness, inflammation, or irritation Swelling of the leg or other affected area.Your health care provider can diagnose this condition by looking at your skin. Tests that may be done include: Punch biopsy of a nodule Throat culture to rule out a strep infection Chest x-ray to rule out sarcoidosis or tuberculosis Blood tests to look for infections or other disorders.The underlying infection, drug, or disease should be identified and treated. Treatment may include: Nonsteroidal anti-inflammatory drugs (NSAIDs). Stronger anti-inflammatory medicines called corticosteroids, taken by mouth or given as a shot. Potassium iodide (SSKI) solution, most often given as drops added to orange juice. Other oral medicines that work on the body's immune system. Pain medicines (analgesics). Rest. Raising the sore area (elevation). Hot or cold compresses to help reduce discomfort.Erythema nodosum is uncomfortable, but not dangerous in most cases. Symptoms most often go away within about 6 weeks, but may return.Call your provider if you develop symptoms of erythema nodosum.Erythema nodosum associated with sarcoidosis Erythema nodosum associated with sarcoidosis Erythema nodosum on the foot Erythema nodosum on the foot.Forrestel A, Rosenbach M. Erythema nodosum.