Chow-chow not walking normally A 6 year old female was noted by the owners to not walk normally. A palpable mass in the midshaft of the left labia was thought to remain as noted on palpation before. A single lateral radiograph was made of the tibia. Radiographic features
- The tibial lesion was expansile in nature with a prominent smooth thin cortical shadow surrounding the lesion. No zone of bone destruction with medullary bone formed of normal cancellous bone. No active periosteal reaction was present. With only one projection, it was not possible to know if the lesion was one surrounding cuff of bone or actually two separate masses.
- No evidence of stifle arthrosis was noted radiographically.
- Palpation during positioning for the radiographic study detected additional bony lesions on the caudal right ribs. Thoracic radiographs were made.
Thoracic radiographs Altered contrast Radiographic diagnosis
- Similar appearing bone lesions were evident on the caudal right ribs that caused marked deformity of the ribs.
- A more radiopaque lesion took origin from the first ribs on the right creating a mass that protruded toward the midline causing a cranial mediastinal mass with severe displacement and narrowing of the trachea. A similar type of displacement of the esophagus was thought probable.
- The radiographic diagnosis was assumed to be multiple osteochondromatosis with probably malignant transformation based on the progression of the clinical signs relativeto the thoracic mass within the past weeks.
Comments
- The owner admitted upon questioning that the dog had a progressive wheezing with increased severity. Vomiting of undigested food had been noted for two weeks.
- Successful surgical removal of the first two ribs on the right was performed. The histopathology was that of an osteosarcoma thought to represent malignant transformation of an osteochondroma.
- Malignant transformation is often the manner in which these previously benign bony lesions attract attention.
- While lesions are often found in the long bones, malignant change is much more frequent in the axial lesions.
