MPA most often occurs in patients between ages 50 and 60 years, but cases have been reported in children and older adults as well. There is a slight male predominance. MPA is most common in patients of Northern European descent.
Complications of MPA include diffuse alveolar hemorrhage, interstitial lung disease, pleural effusion, pulmonary edema, pleuritis, interstitial fibrosis, rapidly progressive focal segmental necrotizing glomerulonephritis, gastrointestinal bleeding, colonic ulcerations, intestinal ischemia, bowel perforation, mononeuritis multiplex, and polyneuropathy.
M31.7 – Microscopic polyangiitis
1144805008 – Microscopic polyangiitis
Differential Diagnosis & Pitfalls
- Granulomatosis with polyangiitis (GPA) – Presence of granulomatous inflammation and upper respiratory tract involvement.
- Eosinophilic granulomatosis with polyangiitis – Associated with peripheral eosinophilia and a history of asthma.
- Cutaneous small vessel vasculitis
- Systemic lupus erythematosus (SLE)
- Polyarteritis nodosa
- Cocaine levamisole toxicity can often present with positive ANCA studies and may mimic vasculitides.
- Drug-induced vasculitis with positive ANCA studies (propylthiouracil, hydralazine, anti-tumor necrosis factor alpha, sulfasalazine, D-penicillamine, minocycline)
- Deep fungal and mycobacterial infections (eg, mucormycosis, tuberculosis) – May have pulmonary symptoms that mimic GPA. Biopsy should demonstrate the causative organisms.
- Pyoderma gangrenosum
- Ecthyma gangrenosum
- Erythema nodosum leprosum
- Immunoglobulin A vasculitis
- Leukemic vasculitis
- Embolism (septic, fat, air, cholesterol, marantic)
- Hypercoagulable state
- Disseminated intravascular coagulation
- Purpura fulminans
- Warfarin necrosis
- Deficiency of adenosine deaminase type 2
- Other collagen vascular diseases (ie, rheumatoid arthritis, dermatomyositis)