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': 'Myasthenia gravis is associated with - \nSelect and explain. \nA. Thymoma, B. Thymic carcinoma, C. Thymic hyperplasia, D. Lymphoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Myasthenia gravis\n\nIt is a muscle disease caused by immune-mediated loss of acetylcholine receptors.\nWhen arising before age 40 years, it is most commonly seen in women, but there is equal occurrence between the sexes in older patients.\nThymic hyperplasia is found in 65% and thymoma in 15% of patients.\nAnalysis of neuromuscular transmission in myasthenia gravis shows a decrease in the number of muscle acetylcholine receptors (AChRs), and circulating antibodies to the AChR are present in nearly all patients with myasthenia gravis,\nPatients show improvement in strength in response to administration of anticholinesterase agents. This remains a most useful test on clinical examination.\nRespiratory compromise was a major cause of mortality in the past', 'role': 'assistant'}]