Mesothelioma

• Definition: malignant tumor that develops from mesothelial cells
• Etiology
  • Secondary to asbestos exposure
  • Alcohol, smoking, and diet do not increase the incidence of mesothelioma.
• Clinical findings
  • Dyspnea and nonpleuritic chest pain (most common)
  • Fever, sweats, weight loss, fatigue
  • Features of pleural effusion: dull percussion; absent or reduced breath sounds on affected side
• Diagnosis
  • Pleurocentesis : bloody (exudative) pleural effusion
  • Imaging (chest x-ray and CT)
    • Multiple nodular pleural lesions (pleural thickening)
  • Laparoscopy, thoracoscopy, and pleuroscopy with stained biopsy: reveal mesothelioma cells and psammoma bodies
    • It is important to differentiate mesothelioma from adenocarcinoma.
      • Immunohistochemistry: Mesothelioma often stains positive for mesothelin, serum mesothelin-related protein (SMRP), calretinin, cytokeratin 5/6 (negative in most adenocarcinomas), and vimentin.
      • Electron microscopy shows tumor cells with long and slender microvilli (in contrast to the short and stubby microvilli found in adenocarcinomas), tonofilaments, and desmosomes.