Signalment & History
- This patient presents to your clinic for a geriatric wellness screening. The owner reports no issues at home other than the patient’s historic mild cough.
Findings
- Centered on the metaphyseal region of the right proximal humerus there is a well-defined area of moth-eaten lysis, characterized by a wide zone of transition and associated moderate, interrupted, spiculated, periosteal proliferation.
- There is a mild diffuse bronchial pattern, characterized by thickening of the bronchial walls. The patient has a large body habitus.
- Additional views of the extremity were obtained.
Diagnosis
- Monostotic, aggressive lesion of the right proximal humerus with moderate adjacent soft tissue swelling. Consider primary osseous neoplasia such as osteosarcoma, most likely.
- Moderate right elbow joint incongruency and osteoarthrosis, likely secondary to angular limb deformity.
Aggressive Bony Lesions
- Can appear radiographically as cortical disruption, an ill-defined zone of transition, and moth eaten osseous lysis.
- Two main differentials for this aggressive radiographic appearance are neoplasia and infection. Considering the location of the lesion (proximal humeral metaphysis) and age of the patient, primary osseous neoplasia is more likely.
- Other common sites to develop primary bone neoplasia in dogs are the metaphyseal region of the following bones: distal femur, distal radius, and proximal and distal tibia.
- Bone tumors can involve the appendicular or axial skeleton and are classified as primary or secondary
- Primary bone tumors include
- Osteosarcoma
- Chondrosarcoma
- Fibrosarcoma
- Hemangiosarcoma
- Osteosarcoma
- Frequently occurs in older, large breed dogs
- Small breeds and young dogs can also be affected
- Most common bone tumor in the dog (95% of all bone tumors)
- Behaves aggressively – local invasiveness and distant metastases
- Usually arise spontaneously from the appendicular skeleton
- Frequently occurs in older, large breed dogs
- Primary bone tumors include
This case was chosen as it was a good example of things that can be missed if you neglect to examine the full radiograph. While there were changes to the pulmonary parenchyma that fit with the patient’s history, it is easy to miss important findings on the periphery of the film if you aren’t careful.
