Small vessel vasculitides

Question 1

Granulomatosis with Polyangitis

Answer 1

General features

• Usually in the 5th decade; more common in men
• Serology: positive for PR3-ANCA
• Triad: involvement of kidneys, lungs and upper airways (nose, sinuses, pharynx)

Morphology

• Kidneys: necrotizing GN  crescents
• Upper airways and lungs: necrotizing-granulomatous vasculitis and necrotizing granulomas
• Lungs: cavitation due to necrosis of small vessels and parenchyma; common in lower lobes

Clinical features

• Kidneys: rapidly progressive GN sy: hematuria, proteinuria, increasing serum creatinine; within 1 year, the patient requires hemodialysis
• Lungs: bilateral nodular infiltrates + cavitation on X-ray
• Chronic sinusitis; nasopharyngeal ulcers  epistaxis

Question 2

Microscopic Polyangiitis

Answer 2

General features

• Necrotizing vasculitis involving arterioles, capillaries, and venules
• All lesions are in the same stage of inflammation
• Serology: MPO-ANCA positivity

Morphology
• Kidneys: necrotizing GN— crescents
• Lungs: alveolar capillaritis—pulmonary hemorrhage
• Skin: neutrophilic infiltration of dermal vessels + fibrinoid necrosis of vessel walls —purpuras
• GI, muscles, etc.

Clinical features

• Kidneys: symptoms of rapidly progressive GN
• Lungs: hemoptysis (spit of blood)
• Skin: vasculitic purpuras
• GI: ulcerations—abdominal pain, melaena; muscles: weakness, myalgias

Question 3

IgA VASCULITIS

Answer 3

General features

• Type III hypersensitivity: immune complex vasculitis with IgA-deposits in arterioles, capillaries and venules
• Mainly in children; most frequent vasculitis in childhood

Morphology

• Necrotizing vasculitis in the skin, the bowels, the joints, and the kidneys
• In the kidneys, immunostaining reveals mesangial deposits of IgA; light microscopy: necrotizing GN  crescents

Clinical features

• Skin: purpuras, principally in the lower extremities
• Bowels: abdominal pain, bleeding
• Joints: arthritis and arthralgia
• Kidneys: hematuria, proteinuria and azotemia.

Outcome
-depends on the extent of crescent formation; overall prognosis is good (formerly: Henoch-Schönlein purpura)