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: Pediatrics
A 10 years old child has lytic lesions in upper femur, the differential diagnosis can be all except : 
Select and explain. 
A. Plasmacytoma, B. Browns tumour, C. Metastasis, D. Histiocytosis
A: Plasmacytoma
Answer: A: Plasmacytoma 
Explanation: Plasmocytoma can be easily ruled out.
It is a localized form of multiple myeloma which usually occurs in 5th to 7th decade.
Metastasis, histiocytosis and brown tumor can cause lytic bone lesions in childhood.