Erythema Nodosum

Erythema Nodosum Summary
Erythema nodosum is a skin inflammation that results in reddish, painful, tender lumps most commonly located in the front of the legs below the knees. Erythema nodosum can resolve on its own in three to six weeks, leaving a bruised area. Treatments include anti-inflammatory medications and cortisone by mouth or injection.
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What is erythema nodosum?

Erythema nodosum is a type of skin inflammation that is located in a certain portion of the fatty layer of skin. Erythema nodosum (also called EN) results in reddish, painful, tender lumps most commonly located in the front of the legs below the knees. The tender lumps, or nodules, of erythema nodosum range in size from one to five centimeters. The nodular swelling is caused by a special pattern of inflammation in the fatty layer of skin.

Erythema nodosum can be self-limited and resolve on its own in three to six weeks. Upon resolution, it may leave only a temporary bruised appearance or leave a chronic indentation in the skin where the fatty layer has been injured.

What causes erythema nodosum?

Erythema nodosum may occur as an isolated condition or in association with other conditions. Conditions that are associated with erythema nodosum include medications (sulfa-related drugs, birth control pills, and estrogens), strep throat, Cat scratch disease, fungal diseases, infectious mononucleosis, sarcoidosis, Behcet's disease, inflammatory bowel diseases (Crohn's disease and ulcerative colitis), and normal pregnancy.

What are the signs and symptoms of erythema nodosum?

Characteristic features of erythema nodosum included raised, tender, reddish nodules, most commonly below the knees in the front of the legs. They are typically painful and can slowly come and go.

There are several scenarios for the outcome of erythema nodosum. Typically, these areas of nodular tenderness range in size from about a dime to a quarter and they may be tender and inflamed off and on for a period of weeks. They usually then resolve spontaneously, each one of the little areas of inflammation shrinking down and then becoming flat rather than raised and inflamed. They leave a bruised appearance. Then, they resolve completely on their own. Other lesions can sometimes pop up elsewhere. This may occur for periods of weeks to months, and then they eventually go away. However, chronic erythema nodosum that may last for years is another pattern. Chronic erythema nodosum, with intermittent recurrences, can occur with or without an underlying disease present.

Medically Reviewed by a Doctor on 8/26/2014

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