Veterinary Society of
Surgical Oncology

Biologic Behaviour

  • primary rib tumors are uncommon and are usually malignant and metastatic
  • OSA is the most common rib tumor in dogs and accounts for 73% of all rib tumors
  • rib OSA had a similar biologic behaviour to appendicular OSA
  • other malignant rib tumors include CSA, FSA, MCT, and HSA
  • malignant rib tumors invade the thoracic wall and can have extensive intrathoracic expansion
  • 27%-45% metastatic rate for rib OSA with metastasis to the lungs very common
  • telangiectatic OSA of the rib is associated with the highest rate of metastasis
  • benign rib tumors include infiltrative lipomas and calcinosis circumscripta

Signalment

  • no sex or breed predisposition
  • large dogs (> 20 kg) over-represented
  • median age 4.5-5.5 years for dogs with OSA and 6 years for dogs with CSA

Clinical Signs

  • firm and fixed thoracic wall mass
  • non-specific signs: pain, weight loss, lethargy, lameness, and dyspnea

Diagnosis

  • primary and metastatic rub tumors may produce lytic, sclerotic, or mixed radiographic patterns
  • primary rib tumors occur in the distal 3rd of rib and usually at the costochondral junction
  • radiographic features are unable differentiate OSA from CSA
  • other radiographic findings: displacement of adjacent ribs and medial displacement of parietal pleura producing extrapleural sign and displacement of intrathoracic structures such as heart and lungs
  • biopsy recommended

Treatment

  • en bloc excision with chest wall reconstruction
  • chest wall can be reconstructed with latissimus dorsi muscle flap, external abdominal oblique muscle flap, diaphragmatic advancement, and prosthetic mesh depending on the size and location of the defect
  • caudal lung lobectomy may be required to permit adequate closure
  • chemotherapy is recommended for dogs with rib OSA

Prognosis

  • MST 120 days for OSA following chest wall resection, with 6-month survival rate 20%
  • MST 240 days for OSA following chest wall resection and chemotherapy is 240 days
  • MST 299-1,080 days for CSA
  • survival times range from 120-450 days for dogs with FSA
  • survival times range from 30-150 days for dogs with HSA
  • prognostic factors: tumor type and complete histologic resection
  • local tumor recurrence ± metastasis is 5.6-times more likely with incomplete resection
Back to top