Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT PART 6-48: ERYTHEMA NODOSUM + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Painful red nodules without ulceration on anterior aspects of legs Slow regression over several weeks to resemble contusions Women are predominantly affected by a ratio of 10:1 over men Some cases associated with infection, inflammatory bowel disease, or drug sensitivity Evaluation for underlying cause is essential +++ General Considerations ++ Erythema nodosum is a symptom complex of panniculitis characterized by tender, erythematous nodules that appear most commonly on the extensor surfaces of the lower legs Most cases are idiopathic; however, they can be considered a skin sign of systemic disease Disease may be associated with various infections Streptococcosis Primary coccidioidomycosis Other deep fungal infections Tuberculosis Yersinia pseudotuberculosis and Y enterocolitica infection Diverticulitis Syphilis May accompany sarcoidosis, Behçet disease, and inflammatory bowel disease May be associated with pregnancy or with use of oral contraceptives + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ The subcutaneous swellings are exquisitely tender and may be preceded by fever, malaise, and arthralgia They are most often located on the anterior surfaces of the legs below the knees but may occur on the arms, trunk, and face The lesions, 1–10 cm in diameter, are at first pink to red; with regression, all the various hues seen in a contusion can be observed +++ Differential Diagnosis ++ Erythema induratum (associated with tuberculosis) Nodular vasculitis Erythema multiforme Lupus panniculitis Poststeroid panniculitis Contusions or bruises Sweet syndrome (acute febrile neutrophilic dermatosis) Subcutaneous fat necrosis (associated with pancreatitis) + Diagnosis Download Section PDF Listen +++ +++ History and Physical Examination ++ History should include inquiring about medication exposures, prior upper respiratory infection, and diarrheal illness Significant physical examination findings include symptoms of any deep fungal infection endemic to the area +++ Laboratory Tests ++ Partial protein derivative (PPD) Blood interferon gamma release assay (such as QuantiFERON) (see Pulmonary Tuberculosis) Two consecutive ASO/DNAse B titers at 2- to 4-week intervals +++ Imaging ++ All patients should have a chest radiograph + Treatment Download Section PDF Listen +++ +++ Medications ++ See Table 6–2 First identify and treat the underlying cause Primary therapy is with nonsteroidal anti-inflammatory drugs Saturated solution of potassium iodide, 5–15 drops three times daily, may result in prompt involution in many cases Systemic therapy directed against the lesions themselves may include use of corticosteroids unless contraindicated by associated infection + Outcome Download Section PDF Listen +++ +++ Prognosis ++ It usually lasts about 6 weeks and may recur If no underlying cause is found, a significant underlying illness (usually sarcoidosis) will develop in only a small percentage of patients over the next year +++ When to Refer ++ If there is a question about the diagnosis, if recommended therapy is ineffective, or specialized treatment is necessary + References Download Section PDF Listen +++ + +Chowaniec M et al. Erythema nodosum—review of the literature. Reumatologia. 2016;54(2):79–82. [PubMed: 27407284] + +De Simone C et al. Clinical, histopathological, and immunological evaluation of a series of patients with erythema nodosum. Int J Dermatol. 2016 May;55(5):e289–94. [PubMed: 26917228] + +Leung AKC et al. Erythema nodosum. World J Pediatr. 2018 Dec;14(6):548–54. [PubMed: 30269303]