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': 'Pleural fibroma is differentiated from mesothelioma by the presence of which of the following in the former-a)  CD14b)  CD24c) Cytokeratin absenced) Erb positivee) CD34 \nSelect and explain. \nA. ce, B. b, C. ac, D. ae', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pleural fibroma (Benign fibrous mesothelioma) \n\nThis is the primary benign lesion of pleura.\nThe tumor is often attached to the pleural surface by a pedicle.\nThese tumor do not usually produce a pleural effusion and have no relationship to asbestos exposure (in contrast to malignant mesothelioma).\nThey consist of dense fibrous tissue with occasional cysts filled with viscid fluid.\nMicroscopically, the tumors show whorls of reticulin and collegen fibers among which are interspersed spindle cells resembling fibroblasts.\nThe tumor cells are CD 34 (+)ve and keratin negative by immunostaining. This feature can be diagnostically useful in distinguishing these lesions from malignant mesothelomas which is CD34 (-)ve and keratin positive.', 'role': 'assistant'}]