This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'A feature of microscopic polyangiitis is - \nSelect and explain. \nA. IgG deposits in kidney, B. Bronchospasm, C. Renal involvement, D. All of the above', 'role': 'user'}, {'content': "Answer: C \nExplanation: Microscopic polyangitis (MPA)\n\nIt is a necrotizing vasculitis.\nIt 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.\nIt is also differentiated from classical PAN by -\n\n\nIt involves lung (in classical PAN lungs are not involved).\nIn kidney it causes glomerulonephritis (in classical PAN, glomerulonephritis is absent).\nIn 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.\nIt is positive for p-ANCA, while classical PAN is not associated with ANCA.\nPresentation\n\nConstitutional symptoms\n\nFever, weight loss, malaise and fatigue.\nKidney (a most common organ involved).\nThere is rapidly progressive glomerulonephritis.\nThe glomerulonephritis is pauci-immune, i.e. there is no immunoglobulin or complement deposition.\nRenal hypertension does not occur, in contrast to classical PAN, where hypertension is the prominant feature of kidney involvement.\n\n\nLung\n\nLung involvement can be dramatic and life threathing.\nCapillaritis causes alveolar hemorrhage.\nHemoptysis, pleuritis and interstitial fibrosis.\n\nSkin\n\nFeatures of small vessel involvement, i.e. purpura, papule.\nInvolves the dependent area of the body, i.e. feet & leg.\nPeripheral nervous system →\xa0Mononeuritis\xa0multiplex\nUpper respiratory tract\xa0\xa0→\xa0Rhinitis, sinusitis, otitis media\nMusculoskeletal system →\xa0Myalgia, arthralgia, Non-destructive migratory arthritis\nEye\xa0→\xa0Conjunctivitis, episcleritis\nNote\nMicroscopic polyangitis has the same spectrum of manifestations as wegener's granulomatosis, but can be differentiated it by following two features -\n\n\nIn wegener's granulomatosis there is granulometous vasculitis i.e. granuloma formation, granulomas are absent in MPA.\nWegener's granulomatosis causes nodules and cavity in the lung.", 'role': 'assistant'}]