This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ohopedics Oncology, Subject name: Orthopaedics
Knee with leg x- ray of an adolescent boy is shown. Probable diagnosis: 
Select and explain. 
A. Chondromyxoid fibroma, B. Osteosarcoma, C. Bone cyst with fracture, D. Osteitis Fibrosis cystica
A: Chondromyxoid fibroma
Answer: A: Chondromyxoid fibroma 
Explanation: Chondromyxoid Fibroma Disease of adolescent Knee X-ray Sclerotic lesion around the coex in the tibia. . Small eccentric lytic lesion which lie parallel to the long axis of the bone. * Bone cyst with fracture will show a larger lesion and is mostly unilateral. * Osteitis Fibrosis cystica will present with multiple lesions and also has a history of abdominal groans, psychic moans and renal stones. * Osteosarcoma is a malignant lesion usually occurs above the joint.