Case Study

CT – Mandibular osteosarcoma in a 11 year old MN Labrador Retriever

History of osteosarcoma confirmed with biopsy. CT performed for surgical planning.

DX

There is a highly aggressive monostotic osteolytic bone lesion compatible with the pre-diagnosed osteosarcoma within the rostral third of the left mandible. The lesion spares the right mandible and the left mandibular corpus caudal to the 4th premolar (307). Reactive lymph node hyperplasia is seen ipsilaterally. Metastatic spread can only be ruled out by sampling.

Image Interpretation

There is a highly aggressive osteolytic process with loss of cortical and medullary bone involving the left rostral mandible from the canine tooth to the 4th premolar (Triadan 304-307). The lesion is primarily osteolytic and expansile to the affected part of the mandibular corpus. The lesion exhibits permative osteolysis with amorphous periosteal reactions. The first and second premolar teeth are lost (Triadan 305 & 306). A soft tissue attenuating mass lesion expands the bone. There is mild generalized loss of the masticatory muscle on the left side noted. The left submandibular lymph nodes show mild generalized enlargement with preserved short to long axis ratio below 0.5. The medial retropharyngeal lymph node is not included in the study.

Outcome

Staging in general should involve regional/sentinel lymph node sampling, chest radiographs and abdominal ultrasound at least prior to surgery. Two options for surgical treatment exist. Both of them should be followed by chemotherapy (example protocol: 5 cycles of cisplatin). Full hemimandibulectomy is the safest procedure. Surgical margins from the symphisis to the mandibular corpus caudal to the first molar (308) is an alternative option, which likely does not improve/facilitate the mastication processes but usually helps prevent asymmetrical prolapse of the tongue at least partially.