Which histologic findings suggest erythema nodosum (EN)?

Updated: May 11, 2020
  • Author: Jeanette L Hebel, MD; Chief Editor: William D James, MD  more...
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Answer

The classic features of erythema nodosum on histopathology include a septal panniculitis with slight superficial and deep perivascular inflammatory lymphocytic infiltrate. [19, 20] The septa of subcutaneous fat usually are thickened. Early-stage lesions demonstrate vascular damage in the septae with neutrophils and eosinophils similar to a leukocytoclastic vasculitis. [21] As lesions evolve, periseptal fibrosis, giant cells, and granulation tissue appear. Miescher granulomas are a hallmark feature of erythema nodosum. Small well-defined nodular aggregates of histiocytes around a central stellate cleft are scattered throughout the lesions. A lymphohistiocytic infiltrate is noted in the septum and in small and medium-sized vessels.


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