Erythema Nodosum: A Practical Approach and Diagnostic Algorithm

Daniela Michelle Pérez-Garza; Sonia Chavez-Alvarez; Jorge Ocampo-Candiani; Minerva Gomez-Flores


Am J Clin Dermatol. 2021;22(3):367-378. 

In This Article

Clinical Presentation

The clinical course of EN is characterized by an acute onset of sensitive and erythematous nodules and plaques of 1–6 cm in diameter (Figure 1a). Lesions are bilateral and symmetric, typically distributed on the distal lower extremities of the pretibial areas, although lesions can also involve the ankles, thighs, and forearms. Erythema nodosum is generally self-limited and resolves within 1–6 weeks by turning from a bright red to a yellow–brown or green-bluish discoloration, resembling bruises (Figure 1b). These bruise-like evolution lesions are known as "erythema contusiformis".[10] Coexistence of lesions in different stages of the evolution can be seen in the same patient. The nodules heal without ulceration, scarring, or atrophy, and recurrences are not uncommon.[1,10,17]

Figure 1.

Clinical features of erythema nodosum (EN). a Erythematous tender nodules bilaterally on the shins. b Bruise-like appearance "erythema contusiformis"

The skin lesions are frequently accompanied by systemic symptoms, such as fever, malaise, headache, gastrointestinal complaints (such as abdominal pain, vomiting, and diarrhea), cough, lymphadenopathy, weight loss, and arthralgia, mainly in the ankles and knees.[18,19] Some of these findings might be suggestive of EN secondary to a systemic disease, and these findings can provide important diagnostic clues.

The diagnosis is usually made in a characteristic clinical scenario and is easily distinguished from other nodular lesions. However, it should be confirmed by a deep incisional or excisional biopsy with a generous portion of subcutaneous fat. Once the pathological diagnosis has been made, the real challenge is the identification of the underlying etiology of EN, if present, before considering it idiopathic.