Erythema Nodosum
The 5 Minute Pediatric Consult
Carmen M. Parrott
DEFINITION
Erythema nodosum is a delayed, cell-mediated hypersensitivity syndrome characterized by red, tender, nodular lesions that are usually on the pretibial surface of the legs and occasionally on other areas of the skin where subcutaneous fat is present.
CAUSES
- Thought to be a result of a host hypersensitivity immune response to circulating immune complexes secondary to infectious and/or inflammatory stimuli, resulting in chronic injury to the blood vessels of the reticular dermis and subcutaneous fat
- There are many associated triggering/under lying diseases:
- In children
- Streptococcal infection and tubercular infection are the most common causes.
- In older patients
- Streptococcus and sarcoidosis are most common.
- Drugs (oral contraceptives, sulfonamides, iodides/bromides, phenytoin)
- Infection (streptococcal infection, tuberculosis, psittacosis, histoplasmosis, yersiniosis, lymphogranuloma venereum, cat-scratch disease, coccidioidomycosis, upper respiratory infection)
- Systemic (sarcoidois, inflammatory bowel disease, Hodgkin disease, Behçet disease)
- Pregnancy
PATHOLOGY
- Septal panniculitis: lymphocytic perivascular infiltrate in the dermis; lymphocytes and neutrophils in the fibrous septa in the subcutaneous fat
- In older lesions, histiocytes, giant cells, and occasionally plasma cells are seen.
- No fat-cell destruction or vasculitis is present.
EPIDEMIOLOGY
- Girls are affected more often than boys.
- Most cases seen in the third decade, but not uncommon after age 10
- Greatest seasonal incidence in spring and fall
- Infection
- Erysipelas/cellulitis
- Superficial or deep thrombophlebitis
- Erythema induratum
- Deep fungal infection
- Angiitis
- Environmental (poisons)
- Tumors
- Trauma
- Bruise
- Metabolic
- Panniculitis secondary to pancreatic disease
- Congenital
- Immunologic
- Major insect bite reaction
- Psychosocial
- Miscellaneous
- Weber-Christian (thighs and trunk) lesions may suppurate and heal with atrophy/localized depression.
PROGNOSIS
- Most individual lesions will completely resolve in 10 to 14 days.
- In general, erythema nodosum resolves in 3 to 6 weeks with or without treatment, unless the underlying cause is a chronic infection or systemic disorder.
- Aching of legs and swelling of ankles may persist for weeks; rarely, symptoms may persist for up to 2 years.
- In children, the recurrence rate is 4% to 10% and is often associated with repeated streptococcal infection.
HISTORY
- In over 50% of patients, a history of arthralgia is noted 2 to 8 weeks prior.
- Prodromal symptoms of fatigue/malaise or upper respiratory infection precedes by 1 to 3 weeks.
- Patients often present with pain and tenderness of extremities, sometimes to the point of difficulty in ambulation.
- Red nodules on anterior lower legs, 2 to 6 cm in diameter
- Overlying skin is normal except for erythema.
- Initially, lesions are bright to deep red with palpable warmth.
- Later, lesions develop a brownish red or violaceous, bruiselike appearance.
- Smaller lesions are slope-shouldered nodules.
- Larger lesions are flat-topped plaques.
SPECIAL QUESTIONS
- Medication history (oral contraceptives, sulfonamides, iodides/bromides)
- Last menses (erythema nodosum is seen in pregnancy)
- History of diarrhea (inflammatory bowel disease or infectious diarrhea)
- TB exposure
PHYSICAL EXAMINATION TRICKS
- Erythema nodosum never ulcerates or supparates.
- Usually, there are no more than six lesions at a time.
- As a rule, both legs are affected.
TESTS
- Throat culture
- Antistreptolysin-O titer
- PPD
- CBC
- ESR
- Stool culture, if history of diarrhea
- Serologic testing, if yersiniosis, histoplasmosis, or coccidioidomycosis suspected
- Chest x-ray study, if diagnosis is in doubt
- Excisional biopsy specimen for histopathology, bacterial and fungal cultures is helpful
False Positives
Bilateral hilar adenopathy may also be seen with coccidioidomycosis, histoplasmosis, TB, streptococcal infection, or lymphomamatosis.
- Identification and treatment of underlying cause
- Bed rest and leg elevation
DRUGS
- Salicylates or other NSAIDs, such as naproxen or indomethacin
- Potassium iodide, 300 mg PO tid for 3 to 4 weeks, especially for cases diagnosed early in course
- Corticosteroids are effective, but rarely necessary.
- Duration: 2 to 4 weeks
WHEN TO EXPECT IMPROVEMENT
- Within 2 to 3 days
- Return visit in 1 week
SIGNS TO WATCH FOR
If lesions recur after cessation of treatment, underlying infection may worsen as well.
| COMMON QUESTIONS AND ANSWERS |
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Q: Will the lesions leave a scar?
A: Erythema nodosum virtually always heals without scarring.
ICD-9-CM 695.2
Hurwitz S. Clinical pediatric dermatology: a textbook of skin disorders of childhood and adolescence, 2nd ed. Philadelphia: WB Saunders, 1993.
Copyright © 2000 Lippincott Williams & Wilkins
M. William Schwartz, Louis M. Bell, Jr., Peter M. Bingham, Esther K. Chung, David F. Friedman and Andrew E. Mulberg, The 5 Minute Pediatric Consult