erythema nodosum

Synopsis

 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

See also

 hypodermitis / panniculitis