Veterinary Society of
Surgical Oncology

Pathophysiology

  • mesothelioma is rare
  • mesothelioma is a tumor arising from mesothelial cells of the pleural and peritoneal cavities
  • sites: thoracic cavity, pericardium, abdominal cavity, and vaginal tunic of the scrotum
  • etiology: congenital form and secondary to asbestos
  • asbestos is a complete carcinogen, initiator, tumor promoter, and causes chromosomal damage
  • asbestos is composed of chrysotile and amphibole fibres
  • amphibole fibres are responsible for the increased risk of mesothelioma
  • histologic types of mesothelioma: epithelial (most common), mesenchymal, and mixed
  • epithelial mesothelioma resembles carcinoma or ADC
  • mixed mesothelioma (= sclerosing mesothelioma): male dogs and GSD are over-represented
  • cystic mesothelioma has been reported in 1 dog

Clinical Signs

  • pleural and peritoneal effusion are the most common presenting signs
  • extensive effusion due to exudation from tumor surface and tumor-obstructed lymphatics
  • acute tamponade and right-sided heart failure with pericardial mesothelioma
  • sclerosing mesothelioma: restrictive disease resulting in vomiting and urinary disease

Diagnosis

  • ultrasonography and survey radiographs are not usually useful as diffuse disease is more common than space-occupying lesions
  • mesothelial cells can exfoliate under many circumstances resulting in difficulty differentiating physiologic mesothelial cell proliferation from neoplasia
  • pericardial fluid pH may differentiate benign and malignant effusions with pH in dogs mesothelioma and HSA > 7.5 while benign effusions have a pH < 6.5
  • fibronectin concentration are increased with neoplasia (sensitive but not specific)
  • definitive diagnosis: histopathology ± immunohistochemistry

Treatment

  • pericardiectomy provides palliation for animals with cardiac tamponade
  • intracavitary cisplatin: well-tolerated with decreased fluid accumulation
  • intracavitary cisplatin combined with systemic chemotherapy may be promising
  • intracavitary cisplatin results in resolution of effusion after 1-2 doses with DFI ranging from 129 days to 27 months

Prognosis

  • MST 13.6 months for pericardial mesothelioma following pericardiectomy, with 1-year survival rate 80% and 2-year survival rate 40%
  • recurrent pleural effusion > 30 days after pericardiectomy associated with a worse prognosis and < 120 days more likely to be associated with mesothelioma

MESOTHELIOMA

Back to top