Mesothelioma

Snapshot

• A 69-year-old woman presents to her primary care physician with complaint of chest discomfort. She describes having shortness of breath and is easily fatigued by routine activities. At the clinic, she is alarmed to see that her weight has dropped more than 10 pounds since she last weighed herself. She has no prior history of smoking. A chest radiograph is obtained and is shown in the image. 

 Introduction

•  Overview
  • mesothelioma is a malignancy involving mesothelial cells that line the body cavities, including the pleura, peritoneum, pericardium, and testis
• Epidemiology
  • incidence
    • ~3,000 cases diagnosed/year in the US
  • demographics
    • men > women
    • 2/3 cases develop in patients ages 50-70
  • risk factors
    • asbestos exposure
      • associated with 80% of cases in US
      • asbestos has been banned since the 1960’s but patients develop mesothelioma 20-40 years after asbestos exposure
    • ↑ cases in polluted areas compared with nonpolluted areas
    • cigarette smoking is NOT a risk factor
• Prognosis
  • median survival for malignant mesothelioma is 11 months
• almost always fatal

 Presentation

•  Symptoms
  • progressive dyspnea
  • non-pleuritic chest wall pain
  • fever
  • fatigue
  • weight loss
  • night sweats
• Physical exam
• pleural effusion noted upon percussion and auscultation

 Imaging

• Chest radiograph
  • findings in malignant pleural mesothelioma
    • obliteration of the diaphragm
    • nodular thickening of the pleura
    • pleural effusion present in > 50% of patients
• CT or MRI of chest 
  • used in the diagnosis of mesothelioma
• identify pleural abnormalities and extent of disease

 Studies

• Thoracentesis
  • performed if pleural effusion is present
  • effusions often hemorrhagic 
• Pleural biopsy
  • may appear as one of three histologic subtypes
    • epithelioid 
      • tumor cells resemble normal mesothelial cells that form a tubulopapillary or trabecular pattern
        
        
    • sarcomatoid 
      • composed of tightly packed spindle cells
    • biphasic (mixed) 
• composed of both epithelioid and sarcomatoid components

 Differential

•  Non-small cell lung cancer 
  • distinguishing factor
    • tumor develops in the lung itself (versus pleural lining)
• Small cell lung cancer 
  • distinguishing factor
• tumor develops in the lung itself (versus pleural lining)

 Treatment

•  Medical
  • chemotherapy for management of malignant mesothelioma
    • cisplatin
    • pemetrexed
    • gemcitabine
  • radiation
    • may provide palliation of chest pain and chest wall metastasis
• Surgical
  • tumor resection
    • may be an option if the disease is confined to the pleural space