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BASICS

  • Vasculitis: inflammatory destruction of blood vessel walls causing ischemia, thrombosis, bleeding, aneurysm.
  • Classified by vessel size:
  • Small vessel (e.g., MPA, GPA, EGPA, IgA vasculitis)
  • Medium vessel (e.g., PAN, Kawasaki disease)
  • Large vessel (e.g., Takayasu arteritis, giant cell arteritis)
  • Variable vessel and single-organ vasculitis (e.g., Behçet disease, cutaneous vasculitis)
  • Can be primary or secondary to infection, malignancy, drugs, or connective tissue diseases.

EPIDEMIOLOGY

  • Highly variable incidence depending on subtype and population.
  • Common vasculitis in clinical practice: hypersensitivity vasculitis.
  • Pediatric vasculitis: Kawasaki disease, IgA vasculitis.
  • TAK prevalent in young Asian women; GCA mostly in Caucasians >50 years.
  • Incidence examples (per million/year):
  • IgA vasculitis: 200-700 (children)
  • GCA: 100-170 (older adults)
  • PAN: 2-33
  • GPA: 4-15
  • MPA: 1-24
  • EGPA: 1-3
  • TAK: 2
  • Primary CNS vasculitis: 2

ETIOLOGY AND PATHOPHYSIOLOGY

  • Three immunopathogenic mechanisms:
  • Immune complex deposition (SLE, IgA vasculitis, cryoglobulinemic vasculitis)
  • ANCA-associated (GPA, MPA, EGPA)
  • T-cell mediated (GCA, TAK)
  • Drug triggers include hydralazine, sulfonamides.
  • Genetic associations:
  • PAN: CECR1 mutation
  • Behçet: HLA-B*51
  • IgA vasculitis: HLA-DQA101:01, HLA-DQB105:01, HLA-DRB1*01:01

RISK FACTORS

  • Combination of genetic predisposition and environmental triggers.
  • Infection-related vasculitis (Hepatitis B, C, HIV, SARS-CoV-2).
  • Autoimmune connective tissue diseases.
  • Drug exposures.

COMMONLY ASSOCIATED CONDITIONS

  • Hepatitis C (cryoglobulinemic vasculitis)
  • Hepatitis B (PAN)
  • SLE, RA, Sjögren, dermatomyositis, MCTD, ankylosing spondylitis
  • Drug-induced (e.g., propylthiouracil)
  • SARS-CoV-2 infection related vasculitis

DIAGNOSIS

History

  • Assess constitutional symptoms: fever, weight loss, malaise.
  • Organ-specific symptoms: neuropathy, visual loss, chest pain, hematuria, abdominal pain, arthralgia.
  • Medication and family history.

Physical Exam

  • Vital signs: hypertension, irregular pulse.
  • Skin: palpable purpura, livedo reticularis, ulcers.
  • Neuro: cranial nerves, sensorimotor exam.
  • Eyes: visual acuity, inflammation.
  • Cardio-pulmonary and abdominal exam.

Differential Diagnosis

  • Fibromuscular dysplasia, embolic disease, drug-induced vasospasm.
  • Thrombotic microangiopathies (DIC, TTP, antiphospholipid syndrome).
  • Systemic infections mimicking vasculitis.
  • Malignancies (lymphoma).
  • Other systemic diseases (Goodpasture, sarcoidosis).

Laboratory and Imaging

  • CBC, creatinine, liver enzymes, urinalysis with microscopy.
  • Autoantibodies: ANA, RF, ANCA (anti-PR3, anti-MPO).
  • Complement levels, cryoglobulins.
  • Infectious serologies (Hep B, C, HIV).
  • Imaging: CXR, CT, MRI, angiography as needed.
  • Biopsy of affected tissue preferred when feasible.

TREATMENT

General Measures

  • Remove inciting agents if drug-induced.
  • Mild pediatric IgA vasculitis may be observed.

Medications

  • First line: corticosteroids (e.g., prednisone 1 mg/kg/day for large vessel vasculitis).
  • Second line: immunosuppressants (cyclophosphamide, methotrexate, azathioprine).
  • Biologics: rituximab, avacopan (ANCA vasculitis); tocilizumab (EGPA); IVIG (Kawasaki).
  • Supportive care and management of organ-specific complications.

Surgery

  • Rare, for repair of tissue damage from vasculitis sequelae.

ISSUES FOR REFERRAL

  • Rheumatology for immunosuppressive therapy.
  • Nephrology for renal involvement.
  • Pulmonology for lung hemorrhage or involvement.

ONGOING CARE

  • Frequent clinical monitoring for relapse.
  • Patient self-monitoring for symptoms.
  • Diet modification as needed for renal or metabolic complications.

PROGNOSIS

  • Good with limited organ involvement.
  • Poor prognosis with renal, intestinal, or lung hemorrhage involvement.
  • Mortality may be due to disease activity or treatment complications.

COMPLICATIONS

  • Early: active vasculitis causing organ damage.
  • Late: therapy-related toxicity and chronic tissue scarring.

REFERENCES

  1. Sunderkötter CH, Zelger B, Chen KR, et al. Nomenclature of cutaneous vasculitis: dermatologic addendum to the 2012 revised International Chapel Hill Consensus Conference nomenclature of vasculitides. Arthritis Rheumatol. 2018;70(2):171-184.
  2. Iba T, Connors JM, Levy JH. The coagulopathy, endotheliopathy, and vasculitis of COVID-19. Res. 2020;69(12):1181-1189.
  3. Walsh M, Merkel PA, Peh CA, et al; PEXIVAS Investigators. Plasma exchange and glucocorticoids in severe ANCA-associated vasculitis. N Engl J Med. 2020;382(7):622-631.

ICD10

  • M31.7 Microscopic polyangiitis
  • M31.30 Granulomatosis with polyangiitis without renal involvement
  • M31.9 Necrotizing vasculopathy, unspecified

Clinical Pearls

  • Suspect vasculitis in patients with palpable purpura, glomerulonephritis, pulmonary-renal syndrome, or mononeuritis multiplex.
  • Always screen for silent renal involvement with serum creatinine, urinalysis, and proteinuria.
  • Vasculitis biopsy may show "skip" lesions; multiple samples may be required.
  • Consider infection, malignancy, or drugs as potential triggers in vasculitis presentation.