Microscopic polyangiitis is best described as which type of vasculitis affecting the microvasculature?

Microscopic polyangiitis is best described as which type of vasculitis affecting the microvasculature?

• A. Large-artery vasculitis
• B. Capillaries, arterioles, and small venules affected
• C. Aorta-centered vasculitis
• D. Venous system-only vasculitis

Answer: (B)

MPA is a small-vessel vasculitis that predominantly involves the microvasculature—the capillaries, arterioles, and small venules. This pattern defines the disease as a pauci-immune necrotizing vasculitis often associated with ANCA and commonly affecting kidneys and lungs. It’s not a disease of large arteries or the aorta, and it’s not limited to the venous system. Therefore, describing it as affecting capillaries, arterioles, and small venules best captures its microvascular targeting.

MPA is a small-vessel vasculitis that predominantly involves the microvasculature—the capillaries, arterioles, and small venules. This pattern defines the disease as a pauci-immune necrotizing vasculitis often associated with ANCA and commonly affecting kidneys and lungs. It’s not a disease of large arteries or the aorta, and it’s not limited to the venous system. Therefore, describing it as affecting capillaries, arterioles, and small venules best captures its microvascular targeting.