February 2014 Small animal case

Dog dobermann.

Male castrated 13 years of age.

Presented with severe, acute lameness, localised on the left elbow.

Radiographs were taken.

Radiographic examination

Craniocaudal (first image) and mediolateral (second image) of the left elbow. Mediolateral view (third image) of the right elbow as comparison.

Radiographic findings

  • There are at least two radiolucent areas on the left elbow: One in the proximocranial part of the olecranon, one in the lateral humeral condyle.
  • The lesion in the olecranon is well defined and round. The cranioproximal border of the olecranon is irregular with focal loss of definition of the cortex (arrows).
  • The lucency in the humeral condyle is ill defined, consisting of multiple, coalascing areas of reduced opacity. The lateral border is irregular as well with focal loss of definition of the cortex (empty arrows).
  • There is increased sof tissue opacity caudal to the distal humerus, ill defined (arrowhead).
  • The radiographic diagnosis was polyostotic aggressive bone lesions, compatible with neopalsia.
  • Differential diagnosis were neoplasia from the soft tissues and secondary bone involvement as synovial cell sarcoma, less likely metastatic process or non neoplastic disease.

Radiographic findings

Close up of the ML view of the left elbow joint.

Radiographic diagnosis

  • 2 bone biopsies were taken from the ulna and from the humerus.
  • The histologic diagnosis was T-cell lymphoma and the dog underwent chemotherapy.
  • 2 months later the dog was presented again with the same clinical signs.
  • Radiographs were taken.

Radiographic examination

Craniocaudal and mediolateral view of the left elbow.

Comments

  • On the second radiographic examination, a pathological fracture is visible accross the humeral condyles with mild dislocation and step formation.
  • There is progression of the lucencies in the ulna and in the humerus, as well as progressive soft tissue swelling.
  • Considering the poor prognosis, the dog was euthanized.
  • The paths of osteolysis (geographic, moth-eaten and permeative) can be correlated with the aggressivity of the bone lesion, with the permeative pattern being the most aggressive.
  • Sometimes, the pattern of lysis is heterogenous, with characteristics of both benign and malignant lesions. In this case, the ulnar lesion may have been interpreted, at first glance, mainly as benign lesion. Considering anyway the simultaneous presence of more criteria of malignancy (cortical lysis, appearance of the humeral lesion, soft tissue involvement), the process must be classified as malignant.
  • Pathologic fracture involve loss of continuitiy in diseased bone, usually as result of minimal trauma. The most common causes of such bone fragility are nutritional (hyperparathyroidism), metabolic, neoplastic.
  • In this case, it has been assumed that the pathologic fracture resulted from a combination of factors: The progression of the lytic process and the surgical procedure to get the bone biopsy.