Erythema nodosum

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Erythema nodosum

Kaveh G Shojania, MD

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review for version 13.2 is current through April 2005; this topic was last

changed on April 8, 2005. The next version of UpToDate (13.3) will be released

in October 2005. INTRODUCTON — Erythema nodosum (EN) is characterized by red

or

violet subcutaneous nodules that usually develop in a pretibial location. It

is presumed to represent a delayed hypersensitivity reaction to antigens

associated with the various infectious agents, drugs, and other diseases with

which

it is associated, although the pathogensis is largely unclear.EPIDEMIOLOGY —

The annual incidence of EN is approximately 1 to 5/100,000 persons, most often

women ages 15 to 40 years [1-5].ETIOLOGY — The majority of patients with EN

have evidence of recent streptococcal infection or have no identifiable cause;

in such cases, symptomatic relief constitutes the only treatment necessary.

However, in 15 to 40 percent of cases, EN represents an early sign of a variety

of infections, connective tissue diseases, and other inflammatory disorders [

1-3,6]. The frequency with which different diseases that have been associated

with EN are found varies with the population studied, as illustrated in Table 1

(show table 1). (See Causes of erythema nodosum section, below). Thus,

careful diagnostic assessment constitutes the most important aspect of

management

for patients presenting with EN.CLINICAL FEATURES — In the majority of cases,

painful, erythematous nodules develop on the anterior surfaces of both legs, and

evolve into bruise-like lesions that resolve without scarring over a two to

eight week period (show picture 1) [2,3,6-9]. The lesions are deep nodules that

may be more easily palpated than visualized. Lesions can also appear on the

thighs, trunk, and upper extremities, but absence of nodules on the legs is

atypical.Polyarthralgias, fever, and malaise frequently accompany the rash

(sometimes in advance of skin findings). The erythrocyte sedimentation rate is

often

elevated, but remains normal in 15 to 40 percent of cases [2,3,5,10].