You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is 12 year old boy presents with progressive swellings at upper end of tibia - irregular, local temperature raised, invariable consistency and ill defined margins most probable diagnosis is and explain in detail?
The clinical presentation in question can occur both in Ewing's sarcoma and osteosarcoma. However, swelling is around the knee joint at upper end of tibia, which ours the diagnosis of osteosarcoma (metaphyseal lesion). Ewing's sarcoma usually occurs in the diaphysis of the bone (middle of the shaft). Giant cell Tumor site- Epiphysis Secondary metastasis occurs in old age usually.