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': 'What is the best method for confirming amyloidosis- \nSelect and explain. \nA. Colonoscopy, B. Sigmoidoscopy, C. Rectal biopsy, D. Tongue biopsy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: “The most definitive\xa0investigation for Amyloidosis is biopsy”.\n\nFor many years rectal biopsy was the first\xa0procedure of choice.\nAn important clinical advance was the recognition that the capillaries in the subcutaneous fat are often involved\xa0in patients with systemic amyloidosis and can often provide sufficient\xa0tissues for the diagnosis of amyloidosis.\xa0\nThus, a biopsy of the organ with the most severe clinical involvement is often unnecessary.\nFor example in cardiac amyloidosis, the definitive\xa0diagnosis of the type of amyloid can be made using an\xa0endomyocardial biopsy specimen with Congo red and immunologic staining of the tissue sample.\nAlternatively, when a noninvasive testing suggests cardiac amyloidosis - A specific\xa0diagnosis is often made by\xa0studying a subcutaneous fat aspiration instead of endomyocardial biopsy thereby avoiding an invasive\xa0procedure.\nWhen the subcutaneous fat aspiration biopsy does not provide information to reach a firm\xa0diagnosis, biopsy\xa0samples can be collected from other organs.\nIn addition, an advantage to performing a biopsy of an involved organ (e.g., kidney heart) is that\xa0it definitively\xa0establishes a cause and effect relationship between the organ dysfunction and amyloid.\nIt is important to realize that not all biopsy sites offer the same sensitivity.\n\nThe best sites of biopsy are: -\n\nAbdominal fat pad and (90% sensitivity)\nRectal mucosa (73% - 84% sensitivity)\n\nOther sites that are often sampled but have poor sensitivity for the diagnosis of amyloid include: -\n\nSalivary glands\nSkin\nTongue\nGingiva\nStomach\nBone marrow', 'role': 'assistant'}]