Erythema nodosum

Erythema nodosum

OVERVIEW:

Clinical pattern of multiple, bilateral, cutaneous, inflammatory, non-ulcerating, non-scarring eruptions that undergo characteristic color changes ending in temporary bruise-like areas. Occurs most commonly on the extensor surface of the shins, less common on thighs and forearms. It is often idiopathic, but may be seen as a response to a variety of clinical entities. Will usually subside in 3 to 6 weeks without scarring or atrophy.

System(s) affected: Skin/Exocrine
Genetics: N/A
Incidence/Prevalence in USA: Unknown
Predominant age: 20-30 years
Predominant sex: Female > Male (3:1)

SIGNS AND SYMPTOMS:

• Raised, warm, tender, brightly erythematous nodules located on anterior shins
• Can also occur on any area with subcutaneous fat
• Diameter 1-15 cm
• Fever, malaise, chills
• Arthralgias
• Bluish discoloration late in course
• Hilar adenopathy
• Episcleral lesions
• Eruptions often preceded by URI symptoms

CAUSES:

• Idiopathic
• Bacterial - streptococcal infections, tuberculosis, leprosy, Yersinia enterocolitica, tularemia, Campylobacter, salmonella, Shigella, gonorrhea
• Sarcoid
• Drugs - sulfonamides, oral contraceptives, bromides
• Pregnancy
• Deep fungal - dermatophytes, coccidioidomycosis, histoplasmosis, blastomycosis
• Viral/chlamydial - infectious mononucleosis, lymphogranuloma venereum, paravaccinia
• Enteropathies - ulcerative colitis, Crohn's disease
• Malignancies - lymphoma/leukemia, sarcoma, post radiation therapy

RISK FACTORS:

Listed with Causes

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS:

• Superficial thrombophlebitis
• Cellulitis
• Septic emboli
• Erythema induratum (cold, ulcerating nodules on calves)
• Nodular vasculitis (warm, ulcerating nodules)
• Weber-Christian disease (violaceous, scarring nodules)
• Lupus panniculitis
• Cutaneous polyarteritis nodosa
• Sarcoidosis granulomata
• Lymphoma

LABORATORY:

• Elevated erythrocyte sedimentation rate
• CBC: mild leukocytosis
• Throat culture, ASO titers
• Stool culture and leukocytes if indicated
• Skin testing for mycobacteria if indicated

Drugs that may alter lab results: Antecedent antibiotics may affect cultures
Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS:

• Septal panniculitis
• Neutrophilic infiltrate in septa of fat tissue, early in course
• Mononuclear cells and histiocytes predominate, late in course
• Lower dermis/subcutis involvement and septal fibrosis may occur

SPECIAL TESTS:

N/A

IMAGING:

Chest x-ray for hilar adenopathy or infiltrates

DIAGNOSTIC PROCEDURES:

Deep skin excisional biopsy including subcutaneous fat. Usually not necessary.

TREATMENT

APPROPRIATE HEALTH CARE:

Outpatient

GENERAL MEASURES:

• Wet dressings (hot soaks and topical medications are not useful)
• Discontinue potentially causative drugs
• Treat underlying disease

SURGICAL MEASURES:

N/A

ACTIVITY:

• Bedrest, keep legs elevated
• Elastic wraps or support stockings may be helpful if patients want to be up and around

DIET:

No restrictions

PATIENT EDUCATION:

• Lesions will resolve over a few months
• No scarring is anticipated
• Joint aches and pains may persist
• Less than 20% recur

MEDICATIONS

DRUG(S) OF CHOICE:

• Medication usually more effective after initial onset versus with chronic disease
• Recurrence is common following cessation of therapy
• Nonsteroidal anti-inflammatory drugs (NSAIDs):
• Aspirin: 325 mg 8-12 per day; use enteric coated to decrease GI upset. Titrate to blood levels.
• Indomethacin: 75-150 mg per day, divided tid
• Naproxen (Naprosyn): 500-1000 mg per day, divided bid

Contraindications:
• Active or recent peptic ulcer disease
• History of NSAIDs hypersensitivity
Precautions:
• Gastrointestinal upset/bleeding
• Fluid retention
• Dose reduction in elderly, especially those with renal disease, diabetes, heart failure
• May mask fever
• NSAIDs may elevate liver function tests
Significant possible interactions:
• May blunt antihypertensive effects of diuretics and beta-blockers
• NSAIDs can elevate plasma lithium levels
• Caution advised with naproxen or any highly protein-bound drug since it may compete for albumin binding and elevate levels
• NSAIDs can cause significant elevation and prolongation of methotrexate levels

ALTERNATIVE DRUGS:

• Potassium iodide 400-900 mg daily, divided bid-tid
• Corticosteroids only in very severe, refractory cases
• Other NSAIDs

FOLLOW UP

PATIENT MONITORING:

Monthly followup or as dictated by underlying disorder

PREVENTION/AVOIDANCE:

N/A

POSSIBLE COMPLICATIONS:

Vary according to underlying disease. None expected from lesions of erythema nodosum.

EXPECTED COURSE AND PROGNOSIS:

• Individual lesions resolve over 3-6 week course
• Total time course of 6-12 weeks, but may vary with etiologic disease if present
• Joint aches and pains may persist for years
• Lesions do not scar
• One or more recurrences in 12-14% of cases; these occur over variable periods, averaging several years, seen most often with sarcoid, streptococcal infection, pregnancy, and oral contraceptives

MISCELLANEOUS

ASSOCIATED CONDITIONS:

See Causes

AGE-RELATED FACTORS:

Pediatric: Incidence equal male and female
Geriatric: N/A
Others: N/A

PREGNANCY:

May have repeat outbreaks during pregnancy

SYNONYMS:

Dermatitis contusiformis

ICD-9-CM:

695.2 Erythema nodosum

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Medical Diagnosis » E » Erythema nodosum