[An autopsy case of microscopic polyarteritis nodosa resembling Schoenlein-Henoch purpura]

A 86 year-old woman was re-admitted because of purpura of her upper and lower extremities, abdominal pain and blood stools. Seven weeks previously, she underwent a gastrectomy for gastric cancer. After re-admission, proteinuria and hematuria were noted, and the serum creatinine level increased. Two months, after the onset of purpura, she died of pneumonia. On autopsy examination, fibrinoid vasculitis of acute inflammatory stage (II) at small arteries and/or arterioles in the bladder, rectum, lungs, spleen and crescentic glomerulonephritis without immune deposits were observed. A diagnosis of microscopic polyarteritis nodosa (M-PN) was made based on these clinical and histological findings. M-PN refers to systemic vaculitis with segmental necrotizing glomerulonephritis. However, this condition may be difficult to diagnose because vasculitis such as Scholein-Henoch purpura (SHP) and/or hypersensitivity angitis, diseases in which the small arteries and arteroles are mainly affected, occasionally bears a clinical and histological resemblance to M-PN. Because differential diagnosis from SHP was required, this case provided abundant suggestions with regard to the entity of M-PN.