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Erythema Nodosum

Erythema Nodosum is a topic covered in the 5-Minute Clinical Consult.

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  • A delayed-type hypersensitivity reaction to various antigens, or an autoimmune reaction presenting as a panniculitis (1) that affects subcutaneous fat
  • Clinical pattern of multiple, bilateral, erythematous, tender nodules in a typically pretibial distribution that undergo a characteristic pattern of color changes, similar to that seen in bruises. Unlike erythema induratum, the lesions of erythema nodosum (EN) do not typically ulcerate.
  • Occurs most commonly on the shins; less commonly on the thighs, forearms, trunk, head, or neck
  • Often associated with nonspecific prodrome including fever, weight loss, and arthralgia
  • Often idiopathic but may be associated with a number of clinical entities
  • Usually remits spontaneously in weeks to months without scarring, atrophy, or ulceration
  • Uncommon to have recurrences after initial presentation

Pregnancy Considerations
May have repeat outbreaks during pregnancy

Pediatric Considerations
Rare pediatric variant has lesions only on palms or soles, often unilateral; typically has a shorter duration in children than adults


  • 1 to 5/100,000/year
  • Predominant age: 20 to 30 years
  • Predominant sex: female > male (6:1) in adults

  • Varies geographically depending on the prevalence of disorders associated with EN
  • Reported 1 to 5/100,000

Etiology and Pathophysiology

  • Idiopathic: up to 55%
  • Infectious: 44%. Streptococcal pharyngitis (most common), mycobacteria, mycoplasma, chlamydia, mycoplasma, coccidioidomycosis, rarely can be caused by Campylobacter spp., ricketssiae, Salmonella spp., psittacosis, syphilis
  • Sarcoidosis: 11–25%
  • Drugs: 3–10%; sulfonamides amoxicillin, oral contraceptives, bromides, azathioprine, vemurafenib
  • Pregnancy: 2–5%
  • Enteropathies: 1–4%; ulcerative colitis, Crohn disease, Behçet disease, celiac disease, diverticulitis
  • Rare causes: <1% (2)
    • Fungal: dermatophytes, coccidioidomycosis, histoplasmosis, blastomycosis
    • Viral/chlamydial: infectious mononucleosis, lymphogranuloma venereum, paravaccinia, HIV
    • Malignancies: lymphoma/leukemia, sarcoma, myelodysplastic syndrome
    • Sweet syndrome

Risk Factors

See “Etiology and Pathophysiology.”

Commonly Associated Conditions

See “Etiology and Pathophysiology.”

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Stephens, Mark B., et al., editors. "Erythema Nodosum." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116218/all/Erythema_Nodosum.
Erythema Nodosum. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116218/all/Erythema_Nodosum. Accessed April 18, 2019.
Erythema Nodosum. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116218/all/Erythema_Nodosum
Erythema Nodosum [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 18]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116218/all/Erythema_Nodosum.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Erythema Nodosum ID - 116218 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116218/all/Erythema_Nodosum PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -