This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Concepts, Subject name: Pathology
[{'content': "All are malignant tumors, except: \nSelect and explain. \nA. Chloroma, B. Fibromatosis, C. Askin's tumor, D. Liposarcoma", 'role': 'user'}, {'content': 'Answer: B \nExplanation: * Fibromatosis are a group of fibroblastic proliferations. *They are locally aggressive, they do not metastasize.', 'role': 'assistant'}]