Erythema nodosum is a rare inflammatory condition that results in the appearance of red nodules beneath the skin. These nodules may be painful and are most commonly found in the front of the legs below the knees. The onset of erythema nodosum usually occurs between the ages of 18 and 34, and is four times more likely to afflict women.
Erythema nodosum can be caused by an underlying infection or an allergic reaction to certain medications. However, in approximately 50 percent of erythema nodosum cases, there is no discernible cause. Symptoms associated with erythema nodosum usually subside within three to four weeks. Erythema nodosum does not usually require any medical intervention and usually resolves itself within six weeks. However, even after the condition has cleared, the afflicted area may have a temporary bruised appearance or leave a chronic indentation in the skin.
The hallmark symptom of erythema nodosum is the occurrence of red nodules that develop on a fatty layer, which is found directly beneath the skin. These nodules are often firm, warm, sensitive to touch, and may coalesce to form large areas of hardened skin. Additionally, these nodules can range in size from one to five centimeters. Within a few days these nodules may become purplish and will eventually fade over the next several weeks. They are most often found on the shins, but may also appear on other parts of the body including, the arms, legs, neck, and buttocks. An onset of erythema nodosum is frequently preceded by the following symptoms:
- Fatigue or malaise
- Joint pain
- Low-grade fever
- Unexplainable weight loss
These symptoms may occur one to three weeks prior to the appearance of a nodule.
Erythema nodosum is a rare condition. Possessing any of the following risk factors will only minimally increase your risk for this disorder. Some of the risk factors for erythema nodosum include:
- Age. Those that are between the ages of twenty to thirty years old are most commonly afflicted by erythema nodosum.
- Gender. Females are more likely to have erythema nodosum.
For approximately half of the cases of erythema nodosum, the exact cause is unknown. For the other half, erythema nodosum is often associated with a vast array of conditions including:
- Streptococcal infections. This may include strep throat, tonsillitis, and rheumatic fever. Strep throat is the most common cause of erythema nodosum.
- Various viral infections. These may include infectious mononucleosis and hepatitis B.
- Fungal lung infections. These may include coccidioidomycosis or histoplasmosis.
- Psittacosis (parrot fever)
- Lymphogranuloma venereum (an uncommon sexually transmitted disease)
- Inflammatory bowel disease. Conditions such as Crohn's disease or ulcerative colitis may contribute to the onset of erythema nodosum.
- Sensitivity to certain medications. These medications may include sulfa-related drugs, estrogens, progestin, birth control pills, bromides, and Amoxicillin (as well as other penicillins).
- Certain cancers. These include leukemia and lymphoma.
- Autoimmune disorders
In order to diagnose erythema nodosum a doctor will initially perform a comprehensive physical exam and take a medical history. Additionally, the doctor will examine the affected area and will specifically take note of the firmness, color, and size of the nodules. Usually, a doctor can diagnose erythema nodosum based on a physical exam alone. In some cases, additional tests may be necessary to confirm the diagnosis. These tests include:
- Blood and urine samples
- Cultures of various bodily fluids
- Chest x-rays and other imaging test
- PPD (skin test for tuberculosis)
- Biopsy of the affected area. A sample is taken to be examined under a microscope
Most cases of erythema nodosum do not require any medical intervention and will resolve itself over a period of six to eight weeks. Additionally, symptoms associated with erythema nodosum may subside when the underlying cause is treated. The following are over the counter medications, which may ameliorate the symptoms associated with erythema nodosum.
- Non-steroidal Anti-inflammatory Drugs (NSAIDs). These include such medications as Advil, Motrin, or Nuprin. However, NSAIDs should be avoided if you also have Crohn's disease, as these drugs have been known to trigger a flare-up.
- Salicylic Acids or aspirin. These include such medications as Ascriptin, Bayer, or Ecotrin.
For some cases of erythema nodosum the following medications may be prescribed:
Potassium Iodide. This medication is taken as an oral solution for four weeks and may aid in reducing nodules, if taken as soon as possible after the initial flare-up of erythema nodosum.
Steroids. These should only be taken if cancer and an underlying infection have been ruled out as the cause of erythema nodosum.
The following home remedies and lifestyle changes that may also help in reducing the symptoms associated with erythema nodosum
- Applying hot or cold compresses
- Avoiding activities that aggravate your pain until symptoms subside