Granulomatosis with polyangiitis (GPA), previously known as Wegener granulomatosis, is a multisystem necrotizing non-caseating granulomatous c-ANCA positive vasculitis affecting small to medium-sized arteries, capillaries, and veins, with a predilection for the respiratory system and kidneys.
This article discusses granulomatosis with polyangiitis in general. For region-specific radiographic features, please refer to individual articles:
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Epidemiology
There is a slight male predilection, and onset is typically at approximately 50 years of age 8.
Diagnosis
The 1990 American College of Rheumatology criteria requires at least two of the four listed below (sensitivity 88.2% and specificity 92%) 21:
positive biopsy for granulomatous vasculitis
urinary sediment with red blood cells
abnormal chest radiograph
oral or nasal inflammation
Clinical presentation
Presentation depends on which organ systems are involved:
cough and hemoptysis
subacute to chronic history of nasal obstruction, rhinitis, and epistaxis
proteinuria and hematuria
Symptoms related to other organ systems are less frequent, due to a corresponding infrequency of involvement (musculoskeletal symptoms, ocular symptoms, skin changes) 9.
Systemic symptoms such as anorexia, malaise and fever are also common 9.
Pathology
Granulomatosis with polyangiitis results from an immune-mediated vascular injury ref.
The classic triad of organ involvement consists of ref:
lungs: involved in 95% of cases
upper respiratory tract / sinuses: 75-90%
kidneys: 80%
In terms of extent, granulomatosis with polyangiitis can be divided into three types ref:
classical: full triad
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limited: not having the full triad
usually respiratory tract involvement only
renal only involvement has been described but is uncommon 7
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widespread: additional organ involvement 14
skin (50%)
eyes (45%)
peripheral nervous system (35%)
occasionally also other organs, such as the heart and gastrointestinal tract
Microscopic appearance
Histologically, necrotizing granulomas with an associated vasculitis are the dominant feature ref.
Markers
In 90% of cases, c-ANCA (PR3) is positive and the levels correlate with disease activity 8.
Treatment and prognosis
Treatment is typically with cyclophosphamide, methotrexate and/or steroids ref. Agents, such as rituximab, are also used ref.
Without treatment, granulomatosis with polyangiitis is rapidly progressive with death usually occurring within a year of diagnosis, with only 10% of patients surviving 2 years 7. Appropriate medical therapy has dramatically increased long-term survival 7.
History and etymology
The former name "Wegener granulomatosis" comes from the German pathologist Friedrich Wegener (1907-1990) who first described it in 1936 11,23. Wegener was a member of the Nazi Party and it is suspected that he took part in, or at least was aware of, experiments on concentration camp inmates 24,25. Following the discovery of his past history, the name "granulomatosis with polyangiitis" has been utilized 15.
Differential diagnosis
General imaging differential considerations include: