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': "Hypersensitivity angiitis is seen in - \nSelect and explain. \nA. SLE, B. Polyarteritis nodosa, C. Henoch schonlein purpura, D. Buerger's disease", 'role': 'user'}, {'content': 'Answer: C \nExplanation: HSP is not hypersensitivity angiitis. But the best answer amongst the given options is HSP because it is the most important differential of hypersensitivity angiitis.\n\nHypersensitivity angiitis \n\nHypersensitivity vasculitis or hypersensitivity angiitis or leukocytoclastic angiitis is a small vessel vasculitis due to hypersensitivity reaction.\nIt is usually to a known drug, e.g. cefoperazone, autoantigens or infectious agents.\nImmune complexes lodge in the vessel wall, attracting polymorphonuclear leukocytes who in turn release tissue-degrading substances leading to an inflammatory process.\nHypersensitivity angiitis usually presents with skin manifestation, e.g. palpable purpura, but sometimes nerves, kidneys, joints and heart may also be involved.\n\nDiagnostic criteria\n\nAt least 3 out of the 5 criteria are required\n\n\nAge > 16\nUse of possible triggering drug in relation to symptoms.\nPalpable purpura\nMaculopapular rash\nSkin biopsy showing neutrophil infiltrate around the vessel.\n\nHenoch-schonlein purpura is the most important differential.', 'role': 'assistant'}]