Skin nontumor


Erythema nodosum

Last author update: 1 July 2011
Last staff update: 7 August 2023

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PubMed Search: Erythema nodosum [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Erythema nodosum. website. Accessed September 22nd, 2023.
Definition / general
  • Panniculitis with tender red nodules, usually on both shins
  • Erythema nodosum migrans (subacute nodular migratory panniculitis, migratory panniculitis): asymmetrical, unilateral and distributed solely on the legs; marked female predominance; older age group
  • Chronic erythema nodosum: nodules appear over months / years; otherwise indistinguishable from typical condition
Clinical features
  • Red, painful, bilateral, symmetrical nodules, elevated above the skin surface
  • On anterior surface of legs, arms, face, calves and trunk
  • Usually involutes in days / weeks, leaving depressed, pigmented lesions
  • No ulceration
  • Immune mediated but precise mechanism is unknown
  • May be associated with streptococcus infection, tuberculosis, sarcoidosis, coccidioidomycosis, ulcerative colitis, Behçet disease, drug reactions or idiopathic; also Hodgkin lymphoma, renal cell carcinoma and carcinomas of colon, pancreas and uterine cervix
Clinical images

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Microscopic (histologic) description
  • A prototype of septal panniculitis, characterized by vascular changes, septal inflammation, hemorrhage and variable acute and chronic panniculitis
  • Both septal and lobular panniculitis
  • Marked septal fibrosis, infiltrated by lymphocytes, neutrophils, histiocytes and granulomas with giant cells
  • Septal infiltrate spills over to affect the fat lobules
  • Dermis shows perivascular and periadnexal chronic inflammatory cell infiltrate
  • Early, the septal inflammation is acute and characterized by neutrophils, soon replaced by lymphocytes and histiocytes
  • Variable eosinophils, variable vasculitis

  • Miescher radial granuloma: characteristic finding of erythema nodosum; septal collection of histiocytes surrounding a cleft (appear to look like spaces); reported in Sweet syndrome, nodular vasculitis and necrobiotic lipodica
Differential diagnosis
  • Nodular vasculitis or subacute nodular migratory panniculitis: usually septal
  • Weber-Christian disease associated panniculitis: usually lobular inflammation
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