Erythema Nodosum: A Practical Approach and Diagnostic Algorithm

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

Disclosures

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

In This Article

Histologic Findings

Erythema nodosum shows characteristic features of a predominantly septal panniculitis without vasculitis (Figure 2a). Early lesions present with hemorrhage and edematous septa with a prominent mixed inflammatory infiltrate consisting of lymphocytes, histiocytes, eosinophils, and numerous neutrophils, infiltrating from the septa to the periphery of the adjacent lobules.[20] Late lesions show effacement of the lobules with fibrotic and thickened septa infiltrated by lymphocytes, histiocytes, multinucleated giant cells, and just a few neutrophils (Figure 2b). The radial Miescher's granulomas consist of small collections of histiocytes arranged around a central star-shaped cleft. This is a relatively specific but not pathognomonic feature. Small- and even medium-sized vasculitis has occasionally been reported.[21]

Figure 2.

Erythema nodosum (EN) histopathological features. Hematoxylin and eosin staining. a A predominantly septal panniculitis, at × 5 magnification. b Lymphohistiocytic infiltrate with the presence of neutrophils and giant multinucleated cells at × 100 magnification

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