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': 'A 50-year-old lady presented with a 3-month history of pain in the lower third of the right thigh. There was no local swelling; tenderness was present on deep pressure. Plain X-rays showed an ill-defined intra medullary lesion with blotchy calcification at the lower end of the right femoral diaphysis, possibly enchondroma or chondrosarcoma. Sections showed a cartilaginous tumor. Which of the following histological features (if seen) would be most helpful to differentiate the two tumours? \nSelect and explain. \nA. Focal necrosis and lobulation, B. Tumor permeation between bone trabeculae at periphery, C. Extensive myxoid change, D. High cellularity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Chondroma (enchondroma) Vs Chondrosarcoma \n\nThe term chondroma is used for benign neoplasm composed of cartilage. It is of two types : -\n\n\nEnchondroma: - Cartilage tumors occurring within the bone.\nPeriosteal chondroma: - Cartilage tumors occurring on the surface of the bone.\n\n\nChondrosarcoma is the malignant tumor of cartilage.\nGrowth potential of chondroma is limited and mostly remain stable, but they have the potential to undergo malignant (sarcomatous) change to become chondrosarcoma. In fact, enchondromas are considered to be a low-grade chondrosarcoma.\nA painful chondroid neoplasm in a large bone in an adult patient can be either enchondroma or chondrosarcoma.\nThe differentiation between a low-grade chondrosarcoma and an enchondroma can be difficult.\nTo make a distinction between these two neoplasms, one has to make use of -\n\n\nCytological changes\nMyxoid quality of stroma\nPermeative characteristics\n\nAmong this permeation, manifested as marrow spaces filled with the neoplasm and entrapment of pre existing bony trabeculae is the most imp\xa0consistent feature of malignancy.', 'role': 'assistant'}]