Background/Purpose:

Microscopic polyangiitis (MPA) is a rare systemic, ANCA (anti-neutrophil cytoplasmic antibody)-associated vasculitis of unclear etiology, characterized by necrotizing small vessel involvement with few or no immune complex deposits.  Necrotizing glomerulonephritis is common. Pulmonary capillaritis causing alveolar hemorrhage and hemoptysis is well-recognized, but most case series are reported in the nephrology literature and emphasize renal considerations (1). We present a single center 10-year retrospective review of 40 patients meeting the Chapel Hill Consensus Conference case definition of MPA, with specific p-ANCA and MPO (myeloperoxidase) positivity, with emphasis on initial and subsequent pulmonary manifestations.

Methods:

We searched the electronic data base as well as separate databases in our laboratory within our large integrated clinic-hospital system and reviewed charts of all patients with related ICD-9 codes for “vasculitis” in the last 10 years.  Patients included in the study were both p-ANCA and MPO positive and met clinical and pathologic criteria for MPA. Patients with only c-ANCA disease or significant granulomata on pathologic evaluation were excluded. Several variables were reviewed (Table 1).

Results:

Onset of illness was usually abrupt and included respiratory symptoms. Most common presenting complaint was cough.  Hemoptysis occurred during the course of illness in 40%.

Pulmonary evaluation included bronchoscopy in 60% and surgical lung biopsy in 12%, usually related to pulmonary hemorrhage.

Treatment doses and duration were quite variable but included combination corticosteroids and cytotoxic therapy in 60%.  Therapy was directed by nephrology in 52.5%.  Rheumatology and Pulmonary directed therapy in 22.5% patients each.  One patient did not undergo therapy.  

The course of illness was variable, with few significant pulmonary relapses.  Hemodialysis occurred in 28%.  Known deaths occurred in twelve, with none directly attributable to the disease process.

Conclusion:

1) Pulmonary involvement is much more frequent than the current literature report of 25-50% when features in addition to hemorrhage are recorded. (1,2)

2) MPA at onset usually includes respiratory symptoms.  Demographic and medical variables failed to identify predisposing factors.

3) No clear guidelines direct the evaluation and management of MPA patients. Consistent communication between pulmonary, nephrology, and rheumatology services could improve our understanding of the disease process.

 

Characteristic	N = 40
Mean Age at Diagnosis	58.9 years  (range:14-83 years)
Gender
Male	37.5%(15)
Female	62.5%(25)
Male:Female ratio	1:1.6
Race
White	73%(29)
Black	5%(2)
Hispanic	20%(8)
Other	2.5%(1)
Vital status as of 2011
Alive	60%(24)
Deceased	30%(12)
Unknown	10%(4)
Smoking history prior to diagnosis	50%(20)
Patients who underwent pulmonary function testing	42.5%(17)
FEV1/FVC >70	70.5%(12 of 17)
Pulmonary involvement only	5%(2)
Renal involvement only	12.5%(5)
Pulmonary and renal involvement	75%(30)
Hemoptysis	40%(16)
Concomitant Medical History
Positive ANA	18(45%)
Hypertension	57.5%(23)
Diabetes mellitus	20%(8)
Cr >1.5 at time of diagnosis	62.5%(25)
Progression to hemodialysis	27.5%(11)
Diagnostic modalities
Bronchoscopy	60%(24)
Renal Biopsy	60%(24)
Lung Biopsy	12.5%(5)
Other Biopsy	10%(4)
Clinical Diagnosis	15%(6)
Treatment
Cyclophosphamide + Corticosteroids	60%(24)
Corticosteroids Alone	10%(4)
Azathioprine Alone	5%(2)
Azathioprine + Corticosteroids	10(4)
Rituximab	5%(2)
Mycophenolate mofetil	12.5%(5)
Cyclophosphamide + Corticosteroids  + Plasmapheresis	5%(2)
Corticosteroids + Rituximab + Mycophenolate +          Plasmapheresis	2.5%(1)
No Treatment	2.5%(1)

REFERENCES:

1. Frankel SK, Cosgrove GP, Fischer A, Meehan RT, Brown KK.  Update in the diagnosis and management of pulmonary vasculitis.  Chest.  2006; 129:452-465.
2. Chung SA, Seo P.  Microscopic Polyangiitis.  Rheumatology Disease Clinic of North America.  2010; 36:545-558.

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