<prompt> All of the following are true regarding Wegeners granulomatosis except: September 2008Affects large size blood vesselsMay affect lungs and kidneysNecrotizing granuloma may be seen on microscopyPR3-ANCAs are present in upto 95 of cases  <response>: Ans. A: Affects large size blood vesselsWegeners granulomatosis is a form of vasculitis that affects the lungs, kidneys and other organs.Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression.Wegeners granulomatosis is pa of a larger group of vasculitic syndromes, all of which feature an autoimmune attack by an abnormal type of circulating antibody termed ANCAs antineutrophil cytoplasmic antibodies against small and medium-size blood vessels.Apa from Wegeners, this category includes Churg-Strauss syndrome and microscopic polyangiitis.Cytoplasmic staining ANCAs that react with the enzyme proteinase 3 cANCA in neutrophils are associated with Wegeners upto 95 of cases.If the patient has renal failure or cutaneous vasculitis, these are the most logical organs to obtain a biopsy from.On histopathological examination, a biopsy will show leukocytoclastic vasculitis with necrotic changes and granulomatous inflammation on microscopy. These granulomas are the main reason for the appellation of Wegeners granulomatosis, although it is not an essential feature. 