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: Surgery
[{'content': 'All are true regarding mesothelioma except? \nSelect and explain. \nA. Bilaterally symmetrical, B. Associated with asbestos exposure, C. Histopathalogy shows biphasic pattern, D. Occurs in late middle age', 'role': 'user'}, {'content': 'Answer: A \nExplanation: • Malignant mesothelioma is MC tumor of the pleura\n• In 20% of malignant mesotheliomas, the tumor arises from peritoneum\n• Exposure to asbestos\xa0is the major known risk factor\n• More common in males, most common after 40 years of age.\n• Three types: Epithelial, sarcomatous, and biphasic\n• Epithelial types are associated with a more favorable prognosis\nPathophysiology\n• Physical characteristics of specific fibers (referred to as serpentine or amphibole) have been shown to be important.\n• Serpentine fibers: Large and curly, not able to travel beyond larger airways.\n• Straight amphibole fibers: In particular the crocidoliteQ fibers navigate distally into the pulmonary parenchyma, most clearly associated with mesotheliomas.\n• Latency period between asbestos exposure and the development of mesothelioma is at least 20 years.\n• Multicentric tumor with multiple pleura-based nodules coalescing to form sheets of tumor (but not bilaterally symmetrical)\n• Natural history of the disease in untreated patients culminates in death due to local extension.\nClinical Features\n• Most patients present with dyspnea and chest pain.\n• Over 90% have a pleural effusion.\nDiagnosis\n• Results of thoracentesis are diagnostic in <10% of patients.\n• Chest X-ray: Pleural effusion, generalized pleural thickening and shrunken hemithorax.\n• Thoracoscopy or open pleural biopsy with special staining of tumor samples is required to differentiate mesotheliomas from adenocarcinomas.\nManagement\n• No effective therapy\n• Treatment options: Supportive care only, surgical resection, and multimodality approaches (using a combination of surgery, chemotherapy, and radiation therapy).', 'role': 'assistant'}]