<prompt> Feature of microscopic polyangitis is -IgG deposits in kidneyBronchospasmRenal involvementAll of the above  <response>: Ans. is c i.e., Renal involvementMicroscopic polvangitis MPAIt is a necrotizing vasculitis.o It is considered as a variant of polyaeritis nodosa PAN, but in contrast to classical PAN, microscopic polyangitis involves smaller vessels, i.e. aerioles, venules and capillaries.o It is also differentiated from classical PAN by ?It involves lung in classical PAN lungs are not involved.In kidney it causes glomerulonephritis in classical PAN, glomerulonephritis is absent.In skin it causes manifestation due to small vessel involvement, i.e. palpable purpura, while classical PAN has manifestation of medium vessel involvement i.e digital ischemia and gangrene, livido reticulars, nodules, papules.It is positive for p-ANCA, while classical PAN is not associated with ANCA.Presentationo Constitutional symptoms Fever, weight loss, malaise and fatigue.o Kidney most common organ involved. There is rapidly progressive glomerulonephritis. The glomerulonephritis is pauci-immune, i.e. there is no immunoglobulin or complement deposition. Renal hypeension does not occur, in contrast to classical PAN, where hypeension is the prominant feature of kidney involvement.o Lung Lung involvement can be dramatic and life threathing. Capillaritis causes alveolar hemorrhage. Hemoptysis, pleuritis and interstitial fibrosis.o Skin Features of small vessel involvement, i.e. purpura, papule. Involves the dependent area of the body, i.e. feet leg.Peripheral nervous system -- Mononeuritix multiplexUpper respiratory tract -- Rhinitis, sinusitis, otitis mediao Musculoskeletal system -- Myalgia, aralagia, Non-destructive migratory ahritiso Eye --- Conjuctivitis, episcleritisNoteMicroscopic polyangitis has same spectrum of manifestations as wegners granulomatosis, but can be differentiated it by following two features ?In wegners granulomatosis there is granulometous vasculitis i.e. granuloma formation, granulomas are absent in MPA.Wegners granulomatosis causes nodules and cavity in the lung. 