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: Orthopaedics
An 11year old boy presented with the complaints of pain in the right arm near the shoulder. X-ray examination revealed an expansile lytic lesion in the upper third of humerus. The most likely diagnosis is - 
Select and explain. 
A. Giant cell tumor, B. Unicameral bone cyst, C. Osteochondroma, D. Parosteal osteosarcoma
B: Unicameral bone cyst
Answer: B: Unicameral bone cyst 
Explanation: Two most important differential diagnosis of expansile lytic lesion in proximal humerus and proximal femur in children are : -


Simple bone cyst (unicameral bone cyst)
Aneurysmal bone cyst


Among these two, only unicameral bone cyst is there in options. Therefore, no further discussion is required.