Clinical features:
(1) red, indurated plaques on the lateral and lower legs, especially the calves
(2) more common in women
(3) marked hypersensitivity to tuberculin in erythema induratum
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Preceding Event
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Term
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tuberculosis
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erythema induratum
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bacterial infection
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nodular vasculitis
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idiopathic
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nodular vasculitis
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Histologic features:
(1) typically a lobular panniculitis with fat necrosis
(2) large vessel granulomatous vasculitis involving an artery or vein (which may take multiple sections to demonstrate)
(3) early lesions show an inflammatory infiltrate that is composed predominantly of neutrophils
(4) later lesions show chronic and granulomatous inflammation, which occasionally may show caseous necrosis
(5) occasionally septal inflammation may be a prominent feature
Differential diagnosis:
(1) sarcoidosis
(2) foreign body granulomas
(3) erythema nodosum
(4) autoimmune disease (polyarteritis nodosa, giant cell arteritis, SLE)
(5) infectious panniculitis
