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
All are true regarding myositis ossificans progressive except - 
Select and explain. 
A. Usually involve childs, B. Progressive form of normal myositis, C. Respiratory problems, D. Ankylosis
B: Progressive form of normal myositis
Answer: B: Progressive form of normal myositis 
Explanation: Myositis ossificans is a misnomer as there is no inflammation in muscles (it is not a form of myositis).
Myositis ossificans progressive begins in childhood, usually before the age of 6 years.
There may be restrictive chest wall disease.
There is fusion (ankylosis) of cervical spine.
Biopsy shows edematous muscle with many inflammatory cells and fragmented myofibrils. Later, true bone forms, often in cartilage, and subsequent mineralizes.