Erythema nodosum


A panniculitis involving subcutaneous fat tissue, usually without vasculitis.

Female to male ratio, 3-1 versus 6-1.

Age of onset is most common in individuals age 15-40 years.

Associated with sarcoid, inflammatory bowel disease, rheumatologic disease, pregnancy, cancer, and adverse reaction to medications and infections.

Associated with bacterial and viral infections, mycoses, drugs including antibiotics and birth control pills, malignant diseases such as lymphoma, leukemia and other malignancies, and systemic diseases such as sarcoidosis, enteropathies, Sweet’s syndrome and Takayasu’s disease.

Associated with arthralgias, hilar lymphadenopathy in Lofgren’s syndrome a form of sarcoidosis.

Streptococcal infections and sarcoidosis are fairly commonly associated diagnoses.

In most cases an underlying diagnosis cannot be made.

Can develop as a delayed hypersensitivity response to streptococcal infections, tuberculosis, fungal infection and leprosy.

Onset is acute and associated frequently with leg edema, malaise, and arthralgias.

Painful lesions occur on front of legs.

The lesions can also appear on the thighs and upper extremities.

Presents as poorly defined, tender erythematosus plaques and nodules.

May be better palpated than visualized.

May be associated with fever and malaise.

May resolve spontaneously.

Lesions usually flatten and become bruise like and leave no residual scars.

New lesions may develop as older lesions disappear.

Ankle edema and leg pain are common associations.

Biopsy usually required to make a definitive diagnosis.

Early histologocally the connective septa are enlarged with edema, fibrin exudation, and white blood cell infiltration, and later infiltration by lymphocytes, histiocytes, multinucleated giant cells and septal fibrosis appear.

Vasculitis is absent from histological findings.

Diagnosis is a clinical one, and streptococcal infection is the most common etiology.

Evaluation a complete blood count, ESR, chemistry profile, ASO titer, chest x-ray and PPD skin test.

Evaluation for systemic causes such as tuberculosis, sarcoidosis, and inflammatory bowel disease is required.

Rarely pregnancy and oral contraceptives are the cause.

Differential diagnosis includes bacterial infections, fungal infections, superficial thrombophlebitis, Behcet’s disease Henoch-Schonlein purpura, and cutaneous vasculitis.

Treatment is symptomatic as the disease process is self limited.

Treatment includes compression stockings, elevation of the extremities and nonsteroidal anti-inflammatory drugs.

Potassium iodine 400-900 mg a day is ineffective adjunctive therapy.

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