Erythema Nodosum

• Erythema nodosum (EN) is an inflammatory skin condition that causes tender, painful red or purple bumps, typically on the shins.
• Causes and risk factors for erythema nodosum include infections, medications, pregnancy, cancer, and other inflammatory conditions.
• Signs and symptoms of erythema nodosum include painful, tender red or purple raised bumps (nodules) on the shins. Other symptoms of EN include joint swelling, redness, or pain, and enlarged lymph nodes in the chest.
• Before the EN nodules appear, symptoms may include joint pain, fatigue, fever, upper respiratory infection symptoms, and feeling unwell (malaise).
• A diagnosis of erythema nodosum can usually be made during a physical examination and history. A doctor will check for underlying illness that may cause EN.
• Erythema nodosum usually does not require treatment. Medications to treat pain from the erythema nodosum nodules include nonsteroidal anti-inflammatory pain medications (NSAIDs), potassium iodide, and oral corticosteroids.
• Home remedies to relieve pain and discomfort include rest, elevating the legs, and compression stockings.
• The prognosis for erythema nodosum is good, and most cases of EN will resolve on their own within a few weeks. Nodules do not leave scars.

Erythema nodosum (EN) is an inflammatory skin condition that causes tender, painful red or purple bumps, typically on the shins. EN is a type of panniculitis, which is inflammation of the fatty layer under the skin.

EN is not a disease in itself but usually a sign of another condition, or a hypersensitivity (allergic) reaction to a drug.

Erythema nodosum is not the same as erythema nodosum leprosum (ENL), which is a complication of a disease called leprosy.

About half of all cases of erythema nodosum have no known cause (they are called idiopathic), but the following conditions commonly trigger erythema nodosum:

• Infection
  • Commonly after a strep throat
  • Tuberculosis
  • Histoplasmosis
  • Coccidioidomycosis (Valley fever)
  • Deep fungal infection
  • Cat scratch disease
• Certain medications
  • Penicillin antibiotics or sulfa drugs
  • Oral contraceptives
  • Bromides
  • Iodides
• Pregnancy
• Cancer
• Inflammatory conditions, including sarcoidosis, Behçet's disease, or gastrointestinal diseases such as ulcerative colitis and Crohn's disease

Risk factors for erythema nodosum include infections, medications, pregnancy, cancer, and inflammatory conditions.

The main symptom of erythema nodosum is painful, tender red or purple raised bumps (nodules) on the shins. Bumps may also appear on the thighs, ankles, buttocks, calves, arms, upper body, or face. The nodules are firm, develop over several days, are usually slightly raised, and about 2 to 5 centimeters in diameter.

Other symptoms of EN include

• joint swelling, redness, or pain that accompany the nodules, and
• enlarged lymph nodes in the chest.

Before the EN nodules appear, a prodrome of symptoms may occur such as

• joint pain,
• fatigue,
• fever,
• upper respiratory infection symptoms, and
• feeling unwell (malaise).

Usually, a medical professionals can make a diagnosis of erythema nodosum during a physical examination and history. There is no specific lab test that would indicate EN. Usually, a doctor will check for illnesses that may cause EN and order tests to find the cause. Testing for underlying conditions may include

• blood tests,
• skin or blood test for tuberculosis,
• throat culture to test for strep,
• chest X-ray, and
• skin sample biopsy.

Erythema nodosum usually does not need treatment. EN typically goes away when an individual receives treatment for the condition that causes it. Medications to treat erythema nodosum include the following:

• Nonsteroidal anti-inflammatory pain medications (NSAIDs)
  • Over-the-counter NSAIDs: ibuprofen (Advil, Motrin) or naproxen (Aleve)
  • Prescription NSAIDs: indomethacin (Indocin, Indocid).
• Potassium iodide (not recommended in patients with tuberculosis)
• Oral corticosteroids (doctors may prescribe a short course if EN is severe and debilitating)

Home remedies may relieve EN pain and discomfort:

• Rest
• Elevating the legs
• Compression stockings
• Applying ice wrapped in a towel to the affected area

A rare type of erythema nodosum is a chronic form called erythema nodosum migrans that may flare up intermittently over several years. The inflammation with chronic EN tends to be less severe than with classic EN.

However, for the most part, complications associated with erythema nodosum are those resulting from the underlying condition that causes the EN.

The prognosis for erythema nodosum is good, and usually EN will resolve spontaneously within a few weeks. As the EN nodules heal, the bumps will get smaller and start to look like bruises. Recovery time is about two to eight weeks and the healed nodules do not leave scars.

About one-third of patients with underlying chronic illnesses may have a relapse of EN.

There is no way to prevent erythema nodosum. Sometimes you can prevent the underlying cause, but since about half the cases of EN have no known cause (are idiopathic), there is no way to prevent it.