Small vessel vasculitides (classification, pathomechanism, symptoms, treatment)

1. Big picture

Small vessel vasculitides affect capillaries, venules, arterioles, and small arteries. Clinically, this means they commonly present with:

• Palpable purpura — skin small vessels
• Glomerulonephritis — renal capillaries
• Pulmonary capillaritis / alveolar hemorrhage — lung capillaries
• Mononeuritis multiplex — vasa nervorum
• ENT disease, asthma, eosinophilia, abdominal pain, arthralgia depending on subtype

The exam logic is:

Purpura + renal urine abnormalities ± lung symptoms = think small vessel vasculitis until proven otherwise.

The most important group for internal medicine is ANCA-associated vasculitis (AAV): granulomatosis with p