This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Musculoskeletal Tumors, Subject name: Radiology
[{'content': 'A 20-year old male patient presents with pain on movement. X-ray of knee joint shows lytic lesion on the upper end of tibia. What is the likely diagnosis? \nSelect and explain. \nA. Simple bone cyst, B. Adamantinoma, C. Multiple myeloma, D. Osteoclastoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans, d. Osteoclastoma (Ref: Apley 9/e p202)A 20-year old male patient presents with pain on movement. X-ray of knee joint shows lytic lesion on the upper end of tibia. In the given X-ray, epiphyseal lytic lesion in tibia with a \'soap bubble\' appearance is characteristic of osteoclastoma. The tumour always abuts against the joint margin in osteoclastoma."X-ray (Giant-cell Tumour): Radiolucent area situated eccentrically at the end of a long bone bounded by subchondral bone plate. The centre sometimes has a soap-bubble appearance due to ridging of the surrounding bone. Appearance of a \'cystic\' lesion in mature bone, extending right up to the subchondral plate, is so characteristic that the diagnosis is seldom in doubt. -- Apley 9/e p202Simple Bone CystAdmantinomaMultiple Myeloma* Fills the medullary cavity but does not expand die boneQ* X-rays: Well-defined radiolucent cyst, often trabeculated & eccentrically placedQ.* In a growing tubular bone it is always situated in the metaphysisQ.* X-ray shows a typical bubblelike defect in the anterior tibia cortex: sometimes there is thickening of the surrounding boneQ* X-rays: The \'classical\' lesions are multiple punched-out defects with \'soft\' margins (lack of new bone) in the skull, pelvis and proximal femur, a crushed vertebra, or a solitary lytic tumour in a large-bone metaphysisQ.Giant-cell Tumour (Osteoclastoma)Giant-cell tumor represents 5% of all primary bone tumoursLesion of uncertain origin that appears in mature bone, most commonly in distal femur, proximal tibia, proximal humerus & distal radiusQ.Hardly ever seen before closure of the nearby physisQCharacteristically it extends right up to the subarticular bone plateQ.Pathology:Aggressive lesions have a poorly defined edge & extend well into the surrounding boneQ.Histology: Striking feature is an abundance of multinucleated giant cells scattered on a background of stromal cells with little or no visible intercellular tissueQ.Tumour has potential to transform into an osteosarcomaQ.Clinical Features:Patient is usually a young adult who complains of pain at the end of a long bone; sometimes there is slight swellingQ.A history of trauma is not uncommon & pathological fracture occurs in 10-15% of cases.Diagnosis:X-ray Findings of Giant-cell Tumour (Osteoclastoma)Radiolucent area situated eccentrically at the end of a long bone & bounded by subchondral bone plateQ.The centre sometimes has a soap-bubble appearance due to ridging of the surrounding boneQ.Appearance of a \'cystic\' lesion in mature bone, extending right up to the subchondral plate, is so characteristic that the diagnosis is seldom in doubtQ.Biopsy is essential. This can be done either as a frozen section before proceeding with operative treatment or (especially if a more extensive operation is contemplated) as a separate procedureQ.Treatment:Well-confined, slow-growing lesions with benign histology can safely be treated by thorough curettage & "stripping" of the cavity, followed by swabbing with hydrogen peroxide or by the application of liquid nitrogen.More aggressive tumours & recurrent lesions: Excision followed by bone grafting', 'role': 'assistant'}]