13, years old boy, the LEAST common cause of proximal lytic lesion of the head of the femur is -
If multiple myeloma occurs as a solitary lesion it is known as Plasmacytoma
Age gp is 6th-7th decade, Rare before 40yrs of age
So the lytic lesion in a 13 yrs old boy cannot be a plasmacytoma
Plasmacytoma
Metastasis
Histiocytosis
Bone tumour