Thoughts about the classification of small vessel vasculitis.

Area of Science:

• Rheumatology
• Immunology
• Nephrology

Background:

• Small vessel vasculitis classification has undergone significant changes over 150 years.
• The discovery of anti-neutrophil cytoplasmic autoantibodies (ANCA) has refocused research on the immunopathogenesis of these conditions.
• Current classification relies on the Chapel Hill Nomenclature.

Purpose of the Study:

• To review the historical classification of vasculitis.
• To present the current nosology based on the Chapel Hill Nomenclature.
• To provide pathogenic and clinical rationale for using the term "ANCA small vessel vasculitis" for specific pauci-immune necrotizing small vessel vasculitides.

Main Methods:

• Literature review of historical classifications.
• Analysis of current vasculitis nomenclature.
• Examination of immunopathogenic and clinical data.

Main Results:

• The classification of vasculitis has evolved from historical descriptions to modern, ANCA-based criteria.
• The Chapel Hill Nomenclature provides a current framework for classifying vasculitis.
• Evidence supports unifying pauci-immune necrotizing small vessel vasculitides under the term "ANCA small vessel vasculitis".

Conclusions:

• The term "ANCA small vessel vasculitis" accurately describes conditions such as microscopic polyangiitis, Wegener's granulomatosis, Churg-Strauss syndrome, and pauci-immune necrotizing glomerulonephritis.
• This unified terminology aids in understanding pathogenesis and clinical presentation.
• Further research into ANCA-associated vasculitides is warranted.