15: Small Vessel Vasculitis Flashcards

1
Q

What are the subclassifications of small vessel vasculitis?

A
  • 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)

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2
Q

What are the sequelae of vasculitis?

A
  • 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
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3
Q

What are the diagnostic approaches for vasculitis?

A
  • Biopsy of involved organs (do NOT biopsy vessels)
  • Radiographic evaluation of involved vessels
    • Conventional angiography
    • CT angiography
    • MR angiography
  • Serology (for AAbs)
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4
Q

What is leukocytoclastic vasculitis?

A
  • 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)
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5
Q

What does this image show?

A

Leukocytoclastic vasculitis

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6
Q

What is purpura?

A

Red/purple discolorations on the skin that do not blanch on applying pressure, caused by bleeding underneath the skin

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7
Q

What are the causes of leukocytoclastic vasculitis?

A
  • ANCA associated vasculitis
  • Cryoglobulinemia
  • IgA vasculitis (HSP)
  • Drug-induced
  • Post-infx
    • Viral
    • Bacterial
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8
Q

What vasculature is involved in ANCA+ vasculitis?

A
  • 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
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9
Q

What is a granuloma?

A
  • 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
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10
Q

What are the patterns of ANCA, and what Ab are they associated with?

A
  • C-ANCA: cytoplasmic pattern
    • anti-proteinase 3 Ab
  • P-ANCA: perinuclear pattern
    • anti-myeloperoxidase Ab
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11
Q

What is the pathogenesis of ANCA-induced inflammation?

A
  1. Loss of tolerance + ANCA AAb production involving T & B cells
  2. ANCA autoimmune response
  3. Neutrophil activation
  4. Acute injury
  5. Innate immune response
    1. Resolution
    2. Sclerotic progression
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12
Q

Anti-PR3 Ab

A
  • Detected with C-ANCA
  • Present in GPA (80-90%)
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13
Q

Anti-MPO Ab

A
  • Detected with P-ANCA
  • Seen with:
    • Microscopic polyangiitis (70-80%)
    • Eosinophilic granulomatosis w/ polyangiitis (50-60%)
    • GPA (<10%)
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14
Q

GPA epidemiology

A
  • 25-60yo
  • No racial/ethnic predilection
  • F:M 1:1
  • Prevalence 5-7/100K
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15
Q

GPA clinical manifestations

A
  • 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
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16
Q

What are the distinguishing features of microscopic polyangiitis?

A
  • Preceding history of upper respiratory tract inflammation uncommon
  • Nongranulomatous vasculitic inflammation
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17
Q

What are the distinguishing features of eosinophilic granulomatosis with polyangiitis?

A
  • Preceding history of asthma or allergic rhinitis
  • Eosinophilia (in peripheral blood and infiltrating tissues)
  • Granulomatous inflammation accompanied by tissue infiltration of eosinophils)
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18
Q

What lab abnormalities are seen in ANCA+ diseases?

A
  • ↑Acute phase reactants (CRP, ESR)
  • Leukocytosis
    • Neutrophilia (GPA, MPA)
    • Eosinophilia (EGPA)
  • Normocomplementemia
  • Urinalysis:
    • Hematuria
    • Proteinuria
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19
Q

What does this image show?

A

Saddle nose deformity (2/2 nasal septal perforation)

20
Q

What does this image show?

A

Subglottic stenosis 2/2 chronic inflammatory response in larynx (may require trach)

21
Q

What does this image show?

A

Cavitating nodules in GPA

22
Q

What does this image show?

A

Crescentic glomerulonephritis in GPA

NB: invasion and destruction of glomerular space is not seen in SLE.

23
Q

Describe anti-IgG immunoflourescent staining of glomeruli in GPA

A

Glomerulonephritis is associated with few or no immune deposits in the glomeruli (pauci-immune glomerulonephritis) on immunofluorescence and electron microscopy; unlike SLE, where deposits are present

24
Q

What does this image show?

A

Dense infiltration of PMNs with compromised blood flow to the nerves; seen with mononeuritis multiplex

25
Q

What are the survival rates with GPA?

A
  • Untreated: 10% at 2 years
  • Treated: 80% at 8 years
26
Q

What is the morbidity associated with GPA?

A
  • Permanent renal insufficiency (42%)
  • Hearing loss (35%)
  • Nasal deformities (28%)
  • Tracheal stenosis (13%)
  • End-stage renal disease (11%)
27
Q

What is the treatment regimen for ANCA-associated vasculitis?

A
  • Induction therapy:
    • Prednisone
    • Cyclophosphamide or **rituximab **(anti-CD20 monoclonal Ab)
  • Maintenance:
    • Subsitute azathioprine (purine antimetabolite) for cyclophosphamide
28
Q

Adverse effects of cyclophosphamide

A
  • Hemorrhagic cystitis –> bladder cancer
  • Premature ovarian failure
  • Infertility
  • Bone marrow suppression
    • Leukopenia
    • Thrombocytopenia
    • Anemia
  • ↑long-term risk of lymphoma or leukemia
29
Q

What is cryoglobulinemia?

A

Systemic inflammatory syndrome that generally involves small-to-medium vessel vasculitis due to cryoglobulin-containing immune complexes

30
Q

What are cryoglobulins?

A

Immunoglobulins that precipitate in the cold (4*C) and dissolve on rewarming

31
Q

What are the classifications of cryoglobulinemia?

A
  • Type I: Monoclonal Ig (e.g., plasma cell malignancy)
  • Type II (mixed): Monoclonal IgM (rheumatoid factor) directed against polyclonal IgG
    • >95% assoc’d w/ chronic HCV infx
  • Type III (mixed): Polyclonal IgM (rheumatoid factor) directed against polyclonal IgG
    • 50% assoc’d w/ chronic HCV infx
    • 50% assoc’d w/ autoimmune dz or lymphoproliferative dz (e.g., SLE)
32
Q

Describe the pathogenesis of mixed cryoglobulinemia

A
  • E2 envelope glycoprotein of HCV binds B cells via CD81 –> lower threshold of activation
  • HCV-infected B cells produce Igs w/ RF activity
  • Immune complex-mediated vasculitis:
    • IgG anti-HCV Ag complexes (+ IF for HCV Ag in vessel wall)
    • RF activity
  • Classic pathway of complement activation
    • Causes hypocomplementemia (C4)
  • ↑serum viscosity in cooler areas of body –> ischemia risk
33
Q

Mixed cryoglobulinemia epidemiology

A
  • Dz of middle/older age (45-55yo)
  • F:M 3:1
  • ↑prevalence Southern Europe
34
Q

Cryoglobulinemia clinical manifestations

A
  • Cutaneous vasculitis (palpable purpura); predilection for lower extremities
  • Arthralgias (not swelling)
  • Peripheral neuropathy (mononeuritis multiplex)
  • Membranoproliferative glomerulonephritis
35
Q

What are the laboratory abnormalities seen in cryoglobulinemia?

A
  • Cryoglobulins
  • Positive HCV Ab or PCR viral load
  • Rheumatoid factor
  • Hypocomplementemia (C4)
  • Proteinuria or hematuria
36
Q

What does this image show?

A

Cryoprecipitite in vessel lumen

37
Q

What does this image show?

A

Subendothelial deposits on mixed cryoglobulinemia EM

38
Q

What is the treatment of mixed cryoglobulinemia?

A
  • Clinically asx:
    • Watch and wait
    • With or without antiviral therapy
  • Cutaneous sx without organ damage:
    • Antiviral therapy
    • With or without corticosteroids
  • Organ damage:
    • Antiviral therapy
    • Corticosteroids
    • Rituximab
  • Rapidly progresive/life-threatening:
    • Plasmapheresis

NB: Antiviral therapy = interferon-alpha + **ribavirin **+ protease inhibitor, OR sofosbuvir

NB2: corticosteroids + rituximab have lowest risk of reactivating HCV

39
Q

What is IgA vasculitis (Henoch-Schonlein Purpura)?

A

small-vesselvasculitis characterized by palpable purpura (most commonly distributed over the buttocks and lower extremities), arthralgias, gastrointestinal signs and symptoms, and glomerulonephritis

40
Q

What vasculature is involved in HSP?

A
  • GI tract submucosal arterioles/venules
  • Kidney glomerulonephritis
  • Skin dermal arterioles/venules
41
Q

HSP epidemiology

A
  • 5-7yo (range 5-15yo)
    • Children 20/100K
    • Most common vasculitis in kids
    • 50% preceded by URI
  • Adults <1/100K
  • M:F = 1.5:1
42
Q

HSP clinical manifestations

A
  • Abdominal pain 2/2 intussusception
  • Renal insufficiency infrequent
    • ​Hematuria/proteinuria
  • Purpura
  • Arthralgia/arthritis
43
Q

HSP lab abnormalities

A
  • ↑serum IgA
  • nl complement levels (>95%)
    • 2/2 IgA not a tivating complement as well as IgG
44
Q

Pathogenesis of HSP

A

Tissue (vascular) deposition of IgA1-containing immune complexes (preceded by viral infx?)

45
Q

True or false: glomerulonephritis in HSP does not commonly result in renal insufficency

A

True; mesangial process, thus does not interfere greatly with renal function

46
Q

HSP treatment

A
  • Benign, self limited process; v. favorable prognosis
  • No indication for immunosuppression
  • Supportive therapy:
    • Hydration
    • Bed rest
    • Analgesia (NSAIDS)