<prompt> A feature of microscopic polyangiitis is -IgG deposits in kidneyBronchospasmRenal involvementAll of the above  <response>: Microscopic polyangitis MPAIt is a necrotizing vasculitis.It is considered as a variant of polyarteritis nodosa PAN, but in contrast to classical PAN, microscopic polyangiitis involves smaller vessels, i.e. arterioles, venules and capillaries.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.PresentationConstitutional symptomsFever, weight loss, malaise and fatigue.Kidney a most common organ involved.There is rapidly progressive glomerulonephritis.The glomerulonephritis is pauci-immune, i.e. there is no immunoglobulin or complement deposition.Renal hypertension does not occur, in contrast to classical PAN, where hypertension is the prominant feature of kidney involvement.LungLung involvement can be dramatic and life threathing.Capillaritis causes alveolar hemorrhage.Hemoptysis, pleuritis and interstitial fibrosis.SkinFeatures of small vessel involvement, i.e. purpura, papule.Involves the dependent area of the body, i.e. feet leg.Peripheral nervous system Mononeuritis multiplexUpper respiratory tract Rhinitis, sinusitis, otitis mediaMusculoskeletal system Myalgia, arthralgia, Non-destructive migratory arthritisEye Conjunctivitis, episcleritisNoteMicroscopic polyangitis has the same spectrum of manifestations as wegeners granulomatosis, but can be differentiated it by following two features -In wegeners granulomatosis there is granulometous vasculitis i.e. granuloma formation, granulomas are absent in MPA.Wegeners granulomatosis causes nodules and cavity in the lung. 