Erythema Nodosum
Last updated: October 8, 2014
Synonym: Panniculitis
ICD-9 Code: 695.2
ICD-9 Code: L52
Definition: Erythema nodosum is an acute, usually self-limited septal panniculitis characterized by tender subcutaneous nodules, typically on the anterior tibial surface.
Etiology: Half of cases have an underlying associated condition (see below). Pathogenesis is unknown but may be related to circulating immune complexes. There is an association with HLA-B8.
Pathology: Acute (neutrophilic) and chronic (granulomatous) septal inflammation is seen in subcutaneous adipose tissue and around blood vessels.
Demographics: Women are predominantly affected, with an M:F ratio of 1:3. It is most common in those between the ages of 25 and 40 years. Incidence has been reported to be two to three cases per 100,000 population.
Disease Associations: It may be idiopathic or seen with some infections (streptococcus, tuberculosis, leprosy, fungal or enteric infections), systemic disorders (Behçet’s syndrome, sarcoidosis, inflammatory bowel disease, pregnancy) or with some drugs (penicillin, sulfonamides, oral contraceptives).
Etiology: Half of cases have an underlying associated condition (see below). Pathogenesis is unknown but may be related to circulating immune complexes. There is an association with HLA-B8.
Pathology: Acute (neutrophilic) and chronic (granulomatous) septal inflammation is seen in subcutaneous adipose tissue and around blood vessels.
Demographics: Women are predominantly affected, with an M:F ratio of 1:3. It is most common in those between the ages of 25 and 40 years. Incidence has been reported to be two to three cases per 100,000 population.
Disease Associations: It may be idiopathic or seen with some infections (streptococcus, tuberculosis, leprosy, fungal or enteric infections), systemic disorders (Behçet’s syndrome, sarcoidosis, inflammatory bowel disease, pregnancy) or with some drugs (penicillin, sulfonamides, oral contraceptives).
Cardinal Findings: There is sudden onset of one or more tender, erythematous or violaceous nodules on the anterior tibial surface, rarely over the thighs or forearms. Lesions are deep nodules, 1 to 10 cm in diameter, that evolve into softer, ecchymotic lesions and usually heal in 6 to 8 weeks without scar formation. In dark-skinned individuals, lesions are usually hyperpigmented. Symptoms such as fever and arthralgia usually relate to the associated condition. Synovitis typically involves the ankles or knees. Loefgren’s syndrome, a specific variant of sarcoidosis, describes the triad of bilateral hilar adenopathy, erythema nodosum, and polyarthralgia or polyarthritis.
Uncommon Findings: Cutaneous ulceration is extremely rare. Migratory and chronic forms have been described.
Diagnostic Tests: A careful clinical search to identify associated conditions should be undertaken. The ESR is usually elevated.
Keys to Diagnosis: Look for tender, erythematous, subcutaneous nodules on anterior tibial surface.
Differential Diagnosis: Erythema nodosum may be confused with vasculitis with nodular lesions, Weber-Christian disease, or panniculitis associated with pancreatitis.
Therapy: Treat any underlying condition. Symptomatic management includes bed rest, cold compresses, and NSAIDs. A short course of systemic corticosteroids or potassium iodide can be very helpful.
Prognosis: Erythema nodosum is usually self-limited, with resolution in 6 to 8 weeks. Prognosis may be determined by the associated disorder, if any.
BIBLIOGRAPHY
Acosta KA, Haver MC, Kelly B. Etiology and therapeutic management of erythema nodosum during pregnancy: an update. Am J Clin Dermatol. 2013; 14: 215-22. PMID: 23625180
Schwartz RA, Nervi SJ. Erythema nodosum: a sign of systemic disease. Am Fam Physician. 2007; 75: 695-700. PMID: 17375516
Requena L, Sanchez-Yus E. Panniculitis. Part I. Mostly septal panniculitis. Am Acad Dermatol 2001;45:163–183. PMID: 11464178
