Dog Labrador retriever 13 Years of age Male intact Presented for pain localised in the right hip joint. Radiographs of the pelvis and right hip joint were taken. Radiographic examination Ventro dorsal view and Faux-profile (mediolateral oblique) projection of the right femur Radiographic findings
- There is an obvious radiolucent fracture line on the proximal diaphysis of the right femur, with step formation, moderate displacement caudally. Mild overriding of the bone fragments with shortening and additional mild rotation.
- In the same area, there is very heterogenous radioopacity of the bony tissue, all in all of reduced opacity. The pattern of lysis is severe and ill defined (permeative pattern, arrows).
- Proximal and more extensively distal to the fracture there is amorphous new bone formation on the cranial aspect of the femur, more organised and lamellar in the most distal part (emtpy arrows). Distal to the fracture and to the described lytic region, there is an areas of increased opacity in the medullary bone extending in the central third of the femoral diaphysis (arrow head).
Radiographic diagnosis Monoostotic aggressive bone lesion with pathologic fracture on the proximal right femur. Close up of the view of the mediolateral view of right femur Comments
- Pathologic fractures are spontanous fractures that occur without a history of overt trauma in abnormal bone weakened by a pre-existing lesion. They may occur also secondary to a trauma of minor intensity.
- Three different pattern of bone lysis have been described:
- Geographic: areas of lysis have well defined margins and are the least aggressive type of lysis (as in bone cysts or abscesses). The cortex may be expanded but usually is not destroyed.
- Moth-eaten lysis consists of multiple discrete areas of lysis of variable size, the cortex may or may not be lytic.
- The most aggressive pattern is permeative lysis, in which focal aeras of ill-defined osteolysis are present throughout a region of bone, sometimes coalescing.
- In case of mixed lysis with radiographic features of different patterns, the most aggressive pattern should be used to characterise the lesion. Differential diagnosis for an aggressive bone lesion are bone tumors or osteomyelitis.
- The dog was euthanized because of very poor general condition. A fine needle aspiration of the lesion was taken but was not diagnostic and the owner declined any further investigation.
