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Fast Five Quiz: The Presentation and Diagnosis of GPA
Formerly known as Wegener granulomatosis, the granulomatosis with polyangiitis (GPA) subtype of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis can impact a variety of organ systems, often presenting with a diverse range of clinical features that complicate timely diagnosis. Knowing how to identify the symptoms and diagnose this rare disease is paramount for adequate treatment.
What do you know about the presentation and diagnosis of GPA? Check your knowledge with this quick quiz.
Upper and lower respiratory tract involvement, along with the skin, eyes, and nervous system (with or without kidney manifestations) are the classic presentations of ANCA vasculitis, with most common presentations of GPA being respiratory, renal, and ear, nose, and throat (ENT) symptoms. ENT manifestations are distinctive and include nasal tissue crusting, mucosal damage causing epistaxis, cartilage deterioration leading to saddle nose deformity, erosive sinus disease, and subglottic stenosis.
Isolated liver involvement in GPA is considered rare. Gastrointestinal involvement can occur in patients with GPA, but it is also not common. Though neurological symptoms can be seen in patients with GPA, isolated involvement is not as common as upper and lower respiratory tract involvement.
Learn more about the presentation of GPA.
MRI is suggested for detecting pachymeningitis and retro-orbital lesions in patients with GPA, with researchers who have evaluated patient cases of GPA stating that the 'exploration of pachymeningitis relies on MRI.' Further, MRI is usually more effective than CT when detecting pachymeningitis.
F-18-fluorodeoxyglucose PET with CT is usually used to detect occult inflammation and exclude malignancy and infection in this population; however, data have shown this method has high sensitivity for detecting cardiovascular, lung, nasal/sinus, and kidney involvements. Standard radiograph is not usually used in this setting.
Learn more about imaging for GPA.
The distinctive renal pathology in GPA is characterized by pauci-immune focal and segmental necrotizing and crescentic glomerulonephritis. This histological pattern features inflammatory destruction of small blood vessels with scant or undetectable immune complex deposits in vessel walls. Microscopic examination of kidney tissue typically reveals areas of fibrinoid necrosis within glomeruli and proliferative changes outside capillaries forming crescents; inflammation of small vessels with neutrophil infiltration and endothelial alterations might be observed as well. When examined with immunofluorescence techniques, the tissue shows minimal or absent staining for immunoglobulins and complement factors, confirming the pauci-immune nature of the condition.
Though membranous nephropathy, minimal change disease, and lupus nephritis are types of glomerulonephritis, they are not characteristic of GPA.
Learn more about renal histology in GPA.
PR3-ANCA shows the strongest association with GPA. Various sources have shown that PR3-ANCA is present in approximately 80% of patients with GPA but can be positive in 2%-27% of patients with microscopic polyangiitis (MPA). Though ANCA testing offers valuable diagnostic insights, clinicians should evaluate results alongside clinical presentations and tissue examinations, since these antibodies occasionally appear in other inflammatory disorders or as medication side effects.
MPO-ANCA is associated with GPA but it is not as common as PR3-ANCA. Anti-neutrophil elastase and ANTI-LAMP2 can be seen with ANCA-associated vasculitis but are not specific for GPA.
Learn more about ANCA detection in GPA.
The presence of lung nodules serves as a key distinguishing feature of GPA when compared with MPA. Although both conditions might present with pulmonary bleeding from capillaritis, nodular formations or cavitary nodules strongly suggest GPA rather than MPA. Conversely, pulmonary fibrosis typically appears in patients with MPA and rarely develops in those with GPA. Interstitial lung disease in an interstitial pneumonia pattern is associated with MPA.
Learn more about pulmonary histology in GPA.
