15: Small Vessel Vasculitis Flashcards
What are the subclassifications of small vessel vasculitis?
- Anti-neutrophil cytoplasmic Ab (ANCA) associated:
- Granulomatosis with Polyangiitis (Wegeners)
- Microscopic Polyangiitis
- Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss syndrome)
- Immune complex mediated
- Cryoglobulinemia
- IgA vasculitis (Henoch-Schonlein purpura)
NB: Immune complex mediated dz confined to smallest vessels (arterioles/capillaries/venules)
What are the sequelae of vasculitis?
- Stenosis and/or occlusion of involved vasculature resulting in organ ischemia or infarction
- Necrosis of vessel wall resulting in aneurysmal dilatation/rupture or intravascular thrombosis causing organ ischemia or infarction
What are the diagnostic approaches for vasculitis?
- Biopsy of involved organs (do NOT biopsy vessels)
- Radiographic evaluation of involved vessels
- Conventional angiography
- CT angiography
- MR angiography
- Serology (for AAbs)
What is leukocytoclastic vasculitis?
- A histological term; NOT a dx
- Most common form of vasculitis of skin
- Typically affects postcapillary venules
- Infiltrating neutrophils exhibit leukocytoclasia (damage by nuclear debris from infiltrating neutrophils in and around the vessels
- Fibrinoid necrosis of vessel walls
- Extravasation of erythrocytes into surrounding tissue (dermis)
What does this image show?
Leukocytoclastic vasculitis
What is purpura?
Red/purple discolorations on the skin that do not blanch on applying pressure, caused by bleeding underneath the skin
What are the causes of leukocytoclastic vasculitis?
- ANCA associated vasculitis
- Cryoglobulinemia
- IgA vasculitis (HSP)
- Drug-induced
- Post-infx
- Viral
- Bacterial
What vasculature is involved in ANCA+ vasculitis?
- Upper respiratory tract arterioles/capillaries
- Lung arterioles and capillaries
- Kidney –> glomerulonephritis
- Peripheral nervous system –> vasa nervorum (small arteries that provide blood supply to peripheral nerves)
- Skin dermal capillaries (and postcapillary venules
What is a granuloma?
- Nodular aggregate of macrophages or cells derived from monocyte-lineage
- Central area of necrosis
- Typically surrounded by rim of lymphocytes (predominantly T cells)
- Commonly associated w/ presence of multinucleated giant cells
What are the patterns of ANCA, and what Ab are they associated with?
-
C-ANCA: cytoplasmic pattern
- anti-proteinase 3 Ab
-
P-ANCA: perinuclear pattern
- anti-myeloperoxidase Ab
What is the pathogenesis of ANCA-induced inflammation?
- Loss of tolerance + ANCA AAb production involving T & B cells
- ANCA autoimmune response
- Neutrophil activation
- Acute injury
- Innate immune response
- Resolution
- Sclerotic progression
Anti-PR3 Ab
- Detected with C-ANCA
- Present in GPA (80-90%)
Anti-MPO Ab
- Detected with P-ANCA
- Seen with:
- Microscopic polyangiitis (70-80%)
- Eosinophilic granulomatosis w/ polyangiitis (50-60%)
- GPA (<10%)
GPA epidemiology
- 25-60yo
- No racial/ethnic predilection
- F:M 1:1
- Prevalence 5-7/100K
GPA clinical manifestations
- Upper respiratory tract
- Chronic sinusitis
- Chronic otitis media
- Subglottic stenosis
- Lower respiratory tract
- Pulmonary cavitating nodules
- Alveolar hemorrhage (hemoptysis)
- Kidney: glomerulonephritis
- PNS: Mononeuritis multiplex (wrist/foot drop)
- Skin: Palpable purpura
- Eyes: Conjuctivitis, retrobulbar inflammation
What are the distinguishing features of microscopic polyangiitis?
- Preceding history of upper respiratory tract inflammation uncommon
- Nongranulomatous vasculitic inflammation
What are the distinguishing features of eosinophilic granulomatosis with polyangiitis?
- Preceding history of asthma or allergic rhinitis
- Eosinophilia (in peripheral blood and infiltrating tissues)
- Granulomatous inflammation accompanied by tissue infiltration of eosinophils)
What lab abnormalities are seen in ANCA+ diseases?
- ↑Acute phase reactants (CRP, ESR)
- Leukocytosis
- Neutrophilia (GPA, MPA)
- Eosinophilia (EGPA)
- Normocomplementemia
- Urinalysis:
- Hematuria
- Proteinuria