This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal infections, Subject name: Anatomy
12 years male came with swelling of lower end tibia which is surounded by rim of reactive bone. what is most likely diagnosis? 
Select and explain. 
A. gaint cell tumour, B. brodie's abscess, C. hypoparathyroidism, D. osteomyelitis
B: brodie's abscess
Answer: B: brodie's abscess 
Explanation: Brodie&;s abscess : seen in immunocompetent host 1. It is along standing localized pyogenic abscess in the bone . 2. It usually involves long bones e.g. upper end of tibia 3. classical brodie&;s abscess looks like a small walled off cavity in bone with little or no periosteal reaction. usual isolated oganism is Staphlococcus aureus ref : maheswari 9th ed