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CA0911DermChallenge_ENodusum
A woman aged 58 years presented to the dermatology clinic with a complaint of painful bruising on both of her legs over the past several weeks. She described the feeling of the lesions as similar to “hard bumps.” The patient reported no recent trauma and had not started any new medications prior to the onset of symptoms. The woman did report a preceding cough and said she had felt “run down” recently. A review of systems was otherwise negative. On examination, several erythematous and tender nodules were noted on the patient’s anterior shins. An examination of the nearby joints was unremarkable. Submit your answer and read the full explanation below. If you like this activity or have a suggestion, tell us about it in the comment box at the bottom of the page. Do you have related images that you would like to share? Click on the “+Image” link under the comment box to upload your photos. By submitting your photo, you agree that the patient in the photo is not identifiable or has signed a waiver in compliance with HIPAA regulations.
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A deep, 4-mm punch biopsy confirmed the suspected diagnosis of erythema nodosum (EN). This inflammatory skin condition is caused by a septal panniculitis, an inflammation of the subcutaneous fat. EN typically presents acutely with clusters of poorly defined erythematous tender nodules on the anterior or lateral aspects of the lower legs.
Less frequently, EN may occur on the upper legs, extensor arms, neck, or face. Lesions are usually symmetrical, measuring 1 to 10 cm in diameter. Early in the disease, the skin overlying the nodules is red and shiny, and the lesions are tense and hard.
Within days to weeks, the nodules flatten, fluctuate, and progress to bluish-purple bruiselike lesions.1 Most lesions eventually resolve within several weeks without any ulceration, scarring, or atrophy. Young women are most frequently affected, although EN occurs in both sexes and all ages.
Patients often report symptoms of flulike illness, malaise or fever. Arthralgia is common at the onset or preceding the eruption. Although any joint may be involved, the ankles, knees, or wrists are affected most frequently. Typical joint symptoms include erythema, edema, and tenderness.
EN is thought to be a reactive process or delayed hypersensitivity reaction to a variety of stimuli. It is most commonly associated with streptococcal infection.2 Sarcoidosis is a very common cause in adults, and when it occurs concurrently with hilar adenopathy, the disease is termed Löfgren’s syndrome.3 TB is a significant etiology in countries where this disease is still endemic. Infection with Yersinia, Salmonella, Campylobacter, or Shigella may precipitate EN. Coccidioidomycosis is the most common cause of EN in the American Southwest.
Drugs that may induce EN include bromides, iodides, sulfonamides, gold salts, penicillin, oral contraceptive pills (OCPs), and hormonal replacement therapies. In addition, ulcerative colitis, Crohn’s disease, and hematologic malignancy—most commonly lymphoma—may cause an eruption.
Finally, pregnancy is an important etiology in many patients.1 Repeated episodes of EN may occur with subsequent pregnancies or with the use of OCPs in sensitive individuals.
Although diagnosis is most often clinical, skin biopsy is helpful in more atypical cases to rule out a nodular vasculitis, insect bites, or other pathology. Deep-skin incisional biopsy is preferred, although a deep punch may be satisfactory. Histopathology reveals a septal panniculitis with no vasculitis. The septa of subcutaneous fat are thickened and infiltrated by inflammatory cells that extend to the periseptal areas of the fat lobules.
The composition of the inflammatory infiltrate differs with stage of the lesion. Initially, edema, hemorrhage, and neutrophils are responsible for the inflammation. As lesions evolve, periseptal fibrosis, lymphocytes, multinucleated giant cells, and granulation tissue appear. Miescher’s radial granulomas are a histopathologic hallmark feature of EN. These are small well-defined nodular aggregates of histiocytes arranged radially around a central stellate cleft.
The differential diagnosis of EN should include other forms of panniculitis. EN migrans — seen mostly in older women — is usually painless and has a more prolonged course. Erythema induratum typically only affects the posterior calves, and lesions may resolve with ulceration or scarring. Subacute localized infections should also be considered.
In addition to skin biopsy, clinical workup usually includes a throat culture or antistreptolysin titer to rule out current or recent infection with group A beta-hemolytic streptococcus. Erythrocyte sedimentation rate is usually high. If clinically indicated, stool examination can exclude infection with common GI illness-causing organisms. A person complaining of cough or pulmonary systems should have a chest x-ray done to exclude sarcoidosis or TB and to document the presence or absence of hilar adenopathy. An intradermal TB skin test should be performed if indicated by history. A comprehensive travel and exposure history is if often necessary to discover other etiologies.
Management of EN involves identifying and treating the underlying etiology, rest and elevation of the affected extremity in the acute stage, and use of such medications as aspirin, colchicine, or other non-steroidal anti-inflammatory agents.
In most patients, EN is self-limiting and resolves within six to eight weeks. Bedrest and use of support hose may hasten recovery. Potassium iodide has been shown to provide quick relief of lesional tenderness, arthralgia, and fever in some patients.4 Intralesional injection of corticosteroids may help control persistent lesions. Systemic corticosteroids are rarely indicated.
Some medications (e.g., aspirin and ibuprofen) that are used to treat EN have been implicated as rare causes of the condition. These agents should be stopped if EN symptoms are exacerbated while the patient is taking them.
In rare instances, EN may become chronic or persistent. Recurrences are more likely if the underlying infection is still present or if the patient resumes regular physical activity too quickly.
The patient in this case was educated regarding the diagnosis and self-limiting nature of the disease. A chest x-ray revealed no pathology, and her screening bloodwork was within normal limits. She was advised to follow up with her primary-care provider for regular health maintenance. In addition, it was recommended that she rest often, use support hose, and take OTC ibuprofen as needed.
Esther Stern, NP-C, is a family nurse practitioner at Advanced Dermatology & Skin Surgery, P.C., in Lakewood, N.J. The author has no relationships to disclose relating to the content of this article.
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References
1. Requena L, Requena C. Erythema nodosum. Dermatol Online J. 2002;8:4.
2. Labbé L, Perel Y, Maleville J, Taïeb A. Erythema nodosum in children: a study of 27 patients. Pediatr Dermatol. 1996;13:447-450.
3. Pettersson T. Sarcoid and erythema nodosum arthropathies. Baillieres Best Pract Res Clin Rheumatol. 2000;14:461-476.
4. Horio T, Imamura S, Danno K, Ofuji S. Potassium iodide in the treatment of erythema nodosum and nodular vasculitis. Arch Dermatol. 1981;117:29-31.
All electronic documents accessed August 15, 2011
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