Granulomatosis with polyangiitis (Wegener granulomatosis)

Granulomatosis with polyangiitis (GPA, previously known as Wegener's granulomatosis) is a systemic vasculitis that affects both small and medium-sized vessels. Patients typically initially suffer from a limited form that may consist of constitutional symptoms and localized manifestations such as chronic sinusitis, rhinitis, otitis media, ocular conditions, and/or skin lesions. In later stages, more serious manifestations may arise, including pulmonary complications and glomerulonephritis, although the skin, eyes, and heart may also be involved. Diagnosis is based on laboratory testing (positive for PR3-ANCA/c-ANCA), imaging, and biopsy of affected organs, which demonstrate necrotizing granulomatous inflammation. GPA is treated with immunosuppressive drugs, typically consisting of glucocorticoids combined with methotrexate, cyclophosphamide, or rituximab. Relapses are common.

• Constitutional symptoms: fever, night sweats, weight loss, arthralgias
• ENT involvement(∼ 90% of cases): often the first clinical manifestation
  • Chronic rhinitis/sinusitis: nasopharyngeal ulcerations → nasal septum perforation → saddle nose deformity
  • In some cases, thick, purulent discharge, sometimes containing blood
  • Oral ulcers
  • Chronic otitis
• Lower respiratory tract (∼ 95% of cases): potentially life-threatening
  • Treatment-resistant, pneumonia-like symptoms with cough, dyspnea, hemoptysis; , wheezing, hoarseness, or pleuritic pain
  • Clinical features of pulmonary fibrosis, pulmonary hypertension, or pulmonary hemorrhage may occur.
• Renal involvement (∼ 80% of cases): potentially life-threatening
  • Pauci-immune glomerulonephritis (Pauci‑immune indicates that there is little evidence of immune complex/antibody deposits.) → rapidly progressive (crescentic) glomerulonephritis (RPGN), with possible pulmonary-renal syndrome
• Skin lesions (∼ 45% of cases)
  • Papules, vesicles, ulcers
  • Purpura of the lower extremities
• Ocular involvement (∼ 45% of cases)
  • Conjunctivitis, episcleritis, retinal vasculitis
  • Corneal ulcerations
• Cardiac involvement (∼ 33% of cases): potentially life-threatening
  • Pericarditis, myocarditis
  • Vasculitis of the coronary arteries; may lead to myocardial infarction and death

Upper respiratory manifestations (i.e., purulent, sometimes bloody discharge; chronic nasopharyngeal infections; saddle nose deformity) are the most common chief complaints!

GPA triad: necrotizing vasculitis of small arteries, upper/lower respiratory tract manifestations, and glomerulonephritis!

References:^[3][6][7]

• Laboratory analysis
  • Blood
    • ↑ Creatinine and ↑ BUN
    • ↑↑ ESR and ↑ CRP
    • Evidence of PR3-ANCA/c-ANCA (anti-proteinase 3): highly sensitive and positive in ∼ 90% of patients
    • Normocytic normochromic anemia (in ∼ 50% of patients)
  • Urine
    • Urinalysis: microscopic hematuria, proteinuria
    • Urine sediment: : dysmorphic RBC and RBC casts; → nephritic sediment
• Imaging
  • Chest x-ray/CT: multiple bilateral cavitating nodular lesions
• Pathology
  • Diagnosis should be confirmed by biopsy of affected tissue
    • Necrotic, partially granulomatous vasculitis of small and medium-sized vessels
    • Necrotizing granulomas (intravascular and extravascular)
    • Glomerulonephritis

A biopsy is necessary to confirm the diagnosis!

References:^[3][6]

	Granulomatosis with polyangiitis (GPA)	Microscopic polyangiitis
Clinical presentation	Glomerulonephritis Localized necrotizing vasculitis Upper/lower respiratory tract manifestations with granulomas	Potentially palpable purpura Nasopharyngeal involvement less common No granulomatous inflammation
Laboratory tests	PR3-ANCA/c-ANCA (anti-proteinase 3)	MPO-ANCA/p-ANCA (anti-myeloperoxidase)

References:^[8]

The differential diagnoses listed here are not exhaustive.

• Remission induction
  • If mild disease; → glucocorticoids + methotrexate (MTX)
    • Patients who do not benefit from MTX may be switched to either cyclophosphamide or rituximab.
  • If moderate to severe disease; → glucocorticoids + either cyclophosphamide or rituximab
    • PCP prophylaxis in patients receiving cyclophosphamide and corticosteroids: trimethoprim/sulfamethoxazole (TMP/SMX)
  • Glucocorticoids should be tapered gradually as soon as the patient begins responding to the immunosuppressant agent.
  • In the case of concurrent Goodpasture syndrome: plasmapheresis
• Remission maintenance : immunosuppressive drugs (e.g., azathioprine, rituximab or methotrexate).

References:^{[1][3][9][10]}