M31.7
BillableMicroscopic polyangiitis
HCC Category Mapping
V28HCC 94 — Reactive and Specified Arthropathies
0.000V24HCC 40 — Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.307ESRDHCC 40 — Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.000RxHCCHCC 84 — Vasculitis and Other Autoimmune Disorders
0.000What This Code Means
A rare autoimmune condition where small blood vessels become inflamed and damaged, causing tissue injury throughout the body.
Coding Tips
- •Microscopic polyangiitis (MPA) is a systemic vasculitis affecting small vessels; document affected organ systems for specificity
- •Distinguish from other vasculitides like granulomatosis with polyangiitis (GPA) which may have different treatment protocols
Clinical Significance
Microscopic polyangiitis is a necrotizing small vessel vasculitis that primarily affects kidneys and lungs, with high risk of organ failure and death if untreated. Early recognition and aggressive immunosuppressive therapy are essential for preserving organ function.
Documentation Requirements
- ✓Clinical evidence of small vessel necrotizing vasculitis
- ✓Renal involvement with glomerulonephritis
- ✓Pulmonary involvement if present
- ✓ANCA testing (typically p-ANCA/MPO positive)
- ✓Biopsy confirmation from affected organs
- ✓Assessment of organ function
- ✓Treatment response monitoring
- ✓Long-term renal and pulmonary function tracking
Excludes 1 — Do NOT code together
- polyarteritis nodosa (M30.0)
Commonly Confused Codes
M31.30 — Wegener's granulomatosis without renal involvement (different ANCA-associated vasculitis)M30.0 — Polyarteritis nodosa (medium vessel involvement)N05.9 — Unspecified nephritic syndrome (isolated renal disease)J84.10 — Pulmonary fibrosis, unspecified (isolated lung disease)M31.1 — Thrombotic microangiopathy (different microvascular process)