Granulomatosis with polyangiitis (GPA) is an antineutrophil cystoplasmic antibody (ANCA)-associated disorder characterized by vasculitis of small- to medium-sized blood vessels and necrotizing granulomatous inflammation in the upper and lower respiratory tract (Chapel Hill, 2012). GPA, formerly known as Wegener granulomatosis, classically involves a triad of organ systems, including the upper respiratory tract, lungs, and kidneys. However, GPA confined to the head and neck is not uncommon.
Diagnosis
Indications for Testing
Persistent upper airway symptoms with other systemic manifestations
Criteria for Diagnosis
- At least two of the following four criteria (American College of Rheumatology [ACR], 1990)
- Sinus involvement
- Lung x-ray with nodules, fixed pulmonary infiltrates, or cavities
- Urinary sediment with hematuria or red cell casts
- Granuloma inflammation within the artery or arteriole
Laboratory Testing
- Nonspecific testing – helpful in excluding other diagnoses or identifying organ dysfunction
- CBC – may demonstrate anemia, thrombocytopenia; helpful to rule out infection
- Urinalysis – hematuria, proteinuria common
- Red blood cell casts often present in fresh urine
- C-reactive protein (CRP)
- Preferred test to detect inflammatory processes (Choosing Wisely: Thirty Things Physicians and Patients Should Question, 2017; American Society for Clinical Pathology)
- Usually elevated
- If CRP not available, order erythrocyte sedimentation rate (ESR)
- ANCA
- Indirect immunofluorescence as initial screen
- If positive – targeted testing for serine antiproteinase 3 (PR3) and myeloperoxidase (MPO)
- Result interpretation
- ANCA presence not necessary for diagnosis if clinical and histological findings are consistent with GPA
- Anti-PR3 – predominates for GPA
- Anti-MPO – nonspecific, less commonly associated with GPA
- Indirect immunofluorescence as initial screen
Histopathology
- Tissue biopsy of involved organ – presence of small artery vasculitis with granulomatous infiltration confirms diagnosis
- Changes tend to be patchy – highest yield from pulmonary biopsy specimen
Prognosis
ANCA titers do not appear to be predictive of relapse (Comarmond, 2014)
Differential Diagnosis
- Infectious
- Mycobacteria spp
- Fungal (eg, Histoplasma capsulatum)
- Vasculitis
- Microscopic polyangiitis
- Antiglomerular basement membrane disease (Goodpasture syndrome)
- Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome)
- Single-organ ANCA-associated vasculitis
- Connective tissue disease
- Granulomatous disease
- Sarcoidosis
- Lymphomatoid granulomatosis
- Lymphoproliferative disease
Background
Epidemiology
- Incidence – 5-10/million worldwide (Lutalo, 2014)
- Age (Lutalo, 2014)
- 55 years (mean age of diagnosis)
- Peaks in seventh decade
- Rare in children
- Sex – M:F, equal (Lutalo, 2014)
Clinical Presentation
- Constitutional – weight loss, fever, myalgias, malaise
- Otorhinolaryngologic – most patients have involvement
- Otologic – serous otitis media, sensorineural hearing loss
- Rhinologic – congestion, rhinorrhea, anosmia, sinusitis, septal perforation, ulcers, cartilage weakening (saddleback nose)
- Laryngeal/tracheal – subglottic or tracheal stenosis
- Pharyngeal – ulcers, granulomatosis lesions
- Pulmonary – cough, dyspnea, pulmonary hemorrhage, wheezing
- Renal – glomerulonephritis, proteinuria, hematuria
- Less common at diagnosis than upper and lower airway involvement, but develops in most patients during disease course
- Ophthalmologic – episcleritis, keratitis, uveitis, retinal hemorrhages
- Cardiovascular – pericarditis, cardiac ischemia, arrhythmias, valvular disease
- Neurologic – mononeuropathy multiplex, sensorimotor polyneuropathy, seizures, central nervous system palsies
- Dermatologic – palpable purpura, ulcers, Raynaud phenomena, headache, seizures
- Limited disease – may occur without evidence of systemic vasculitis
- Most often limited to otorhinolaryngologic involvement
ARUP Laboratory Tests
Preferred test for evaluation of suspected vasculitis
Quantitative Immunoturbidimetry
Preferred first-line reflex panel for the evaluation of ANCA-associated vasculitis
Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay
Comprehensive panel for the evaluation of ANCA-associated vasculitis
Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay
Use to monitor previously established MPO/PR3 antibodies or confirm an indirect fluorescent antibody (IFA) ANCA positive test result
Test does not include ANCA testing by IFA
For ANCA testing, refer to the available panel tests
For the workup of suspected vasculitis, refer to ANCA-associated vasculitis profile (ANCA/MPO/PR3) with reflex to ANCA titer
For patients with a history of vasculitis, refer to ANCA with reflex to titer and MPO/PR3 antibodies
Semi-Quantitative Multiplex Bead Assay
References
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