Doctor's Notes on Erythema Nodosum
Erythema nodosum (EN) is an inflammatory skin condition (panniculitis) that causes tender, painful red or purple bumps or nodules that usually appear on the shins but may appear at other sites (ankles, thighs, buttocks, upper body and face, for example). Signs and symptoms include development over several days and raised nodules about 2-5 cm in diameter. Joint pain, redness and/or swelling may occur along with enlarged lymph nodes in the chest. However, some symptoms may develop before the nodules appear such as joint pain, fatigue, fever, malaise and respiratory infection symptoms. EN is not considered a disease but is itself a symptom of other conditions like a hypersensitivity to a drug or other medical problems.
About 50% of people that develop EN have no identified cause. However, the following conditions may commonly trigger EN; infections (strep throat, TB, Histoplasmosis and others), drugs or medications (penicillin, sulfas, oral contraceptives, for example), pregnancy, cancer and inflammatory conditions (sarcoid, ulcerative colitis and others).
Erythema Nodosum Symptoms
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,
- upper respiratory infection symptoms, and
- feeling unwell (malaise).
Erythema Nodosum Causes
About half of all cases of erythema nodosum have no known cause (they are called idiopathic), but the following conditions commonly trigger erythema nodosum:
- Certain medications
- Penicillin antibiotics or sulfa drugs
- Oral contraceptives
- Inflammatory conditions, including sarcoidosis, Behçet's disease, or gastrointestinal diseases such as ulcerative colitis and Crohn's disease
Crohn's (or Crohn) disease is a disease that usually affects the small intestine and less commonly the colon, but it is capable of involving the remainder of the gastrointestinal tract - the mouth, esophagus, and stomach. The chronic inflammation that is the basis of Crohn's disease causes ulceration, swelling, and scarring of the parts of the intestine that it involves. Other names for Crohn's disease include granulomatous enteritis, regional enteritis, ileitis, and granulomatous colitis when it involves the colon.
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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.