On the basis of the cases reported, it would seem reasonable to conclude that these pseudotumors may arise, first, from hemorrhages originating in the joint, extending along the bone to produce pressure erosion; second, from subperiosteal hemorrhages, which may at first lead to formation of new bone and later to absorption and destruction of bone; and third, from cortical or medullary hemorrhage, which may lead to cystic changes and later may destroy the bone or lead to fracture and further hemorrhage.
It is difficult in any one case to state accurately which route was followed. On the other hand, it seems important to be able to recognize the condition early enough so that the destructive changes may be kept under control.