Erythema nodosum (nodular erythema)

Erythema nodosum is an acute, painful inflammation of the subcutaneous fatty tissue, which manifests itself as reddish, pressure-sensitive lumps on the lower legs. It is not a disease in its own right, but a reaction of the body to various triggers. The disease occurs more frequently in women than in men, especially between the ages of 20 and 40.

Causes

Common causes are bacterial infections, especially streptococcal infections of the throat, but also tuberculosis. Chronic inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis can trigger erythema nodosum. Sarcoidosis, a systemic inflammatory disease, is also a common cause. Certain medications such as the contraceptive pill, antibiotics or sulphonamides can trigger the disease.

Pregnancy and, in rare cases, fungal or viral infections are also possible triggers. In around 30 to 50 percent of cases, the exact cause remains unknown.

Symptoms

The typical skin changes are painful, overheated, reddish to purple lumps with a diameter of one to five centimeters. They tend to occur symmetrically on the front of both lower legs. The lumps fade over a few weeks and undergo color changes from red to blue-green to yellow-brown, similar to a healing bruise. This may be accompanied by fever, joint pain, fatigue and a feeling of illness.

Diagnosis

The diagnosis is made clinically and through blood tests, which show elevated inflammation levels. Further tests such as a throat swab, X‑ray of the lungs or stool examinations are necessary to find the cause.

Treatment

Treatment depends on the underlying disease. Cool compresses, elevation of the legs, rest and anti-inflammatory medication help symptomatically. Erythema nodosum usually heals without consequences within three to six weeks.