대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Microscopic Polyangiitis (Diffuse Pulmonary Hemorrhage)

Radiologic Findings

Initial chest radiograph shows multiple areas of consolidation in both lungs, cardiomegaly and blunting of both costophrenic angles. CT scans (lung-window images) show multiple areas of round or wedge-shaped consolidation in association with peripheral ground-glass attenuation in both lungs. Findings of bronchial dilatations and areas of air-trapping are also observed in both lungs which has not changed compared with previous high-resolution CT scan obtained 1 year ago.
On laboratory findings, pANCA and RA factor were positive. Steroid treatment and hemodialysis were started. Follow-up chest radiograph obtained 2 months later shows almost complete disappearance of consolidations and decreased cardiac size.

Brief Review

Microscopic polyangiitis ("microscopic polyarteritis") is a form of a non-granulomatous necrotizing small vessel vasculitis that most often affects venules, capillaries, arterioles, and small arteries, although it occasionally involves medium-sized arteries. Microscopic polyangiitis is a more appropriate name than microscopic polyarteritis because some patients have no evidence for arterial involvement. The absence or paucity of immunoglobulin localization in vessel walls distinguishes microscopic polyangiitis from immune complex mediated small vessel vasculitis, such as Henoch-Schonlein purpura and cryoglobulinemic vasculitis. Clinical, epidemiological, and pathologic differences warrant the separation of microscopic polyangiitis from polyarteritis nodosa on the basis of involvement of capillaries and venules, positive myeloperoxydase-antineutrophil cytoplasmic antibody (P-ANCA) (70-93%), and an active urine sediment by the former but not the latter. Pauci-immune necrotizing and crescentic glomerulonephritis, and hemorrhagic pulmonary capillaritis are common in patients with microscopic polyangiitis. Microscopic polyangiitis is the most common cause for pulmonary-renal vasculitic syndrome. The vasculitis in patients with microscopic polyangiitis is pathologically indistinguishable from the vasculitis of Wegener's granulomatosis and Churg-Strauss syndrome. Granulomatous inflammation distinguishes Wegener's granulomatosis from microscopic polyangiitis. Asthma and eosinophilia distinguish Churg-Strauss syndrome from microscopic polyangiitis. Microscopic polyangiitis, Wegener's granulomatosis, and Churg-Strauss syndrome are all associated with circulating antineutrophil cytoplasmic autoantibodies.
Clinical manifestations are highly polymorphic, but rapidly progressive glomerulonephritis is one of the most frequent and most severe manifestations of the disease. Other systemic findings include pulmonary hemorrhage (12-29%), musculoskeletal involvement (65-72%), purpura (44-58%), abdominal pain (32-58%), digestive tract bleeding (29%), peripheral neuropathy (14036%), and ocular, ear, nose and throat lesions.
Biopsy of an affected organ and detection of circulating anti-neutrophil cytoplasmic antibodies (pANCA) are key elements for the positive diagnosis of microscopic polyangiitis. Biopsies can disclose necrotizing vasculitis affecting small vessels, without granulomas and without immune deposits.
Treatment of severe forms of microscopic polyangiitis is based on the administration of pulse methylprednisolone, oral corticosteroids and cyclophosphamide. Treatment induces a complete remission of the disease in more than 90% of cases, but about 30% of the patients will experience a relapse, and progressive worsening of renal function can occur in patients with severe chronic renal failure. Deaths is related to vasculitis or side effects of treatment.

References

1. Jennette JC, Thomas DB, Falk RJ. Microscopic polyangiitis (microscopic polyarteritis). Semin Diagn Pathol 2001 Feb;18(1):3-13
2. Handa R, Wali JP, Gupta SD, Dinda AK, Aggarwal P, Wig N, Biswas A. Classical polyarteritis nodosa and microscopic polyangiitis--a clinicopathologic study. J Assoc Physicians India 2001 Mar;49:314-9
3. Venetz JP, Rossert J. Microscopic polyangiitis. Ann Med Interne (Paris) 2000 May;151(3):193-8

Keywords

Lung, Vascular, Vasculitis, ANCA associated vasculitis,