Malignant Mesothelioma

Ayodale SA Johnson Odulate, MD - Case Coordinator
Anu Bansal, MD - Radiology Discussion
David W Kindelberger, MD - Pathology Discussion
Steven E Seltzer, MD - Attending Radiologist

September 22, 2003

Presentation

Imaging Findings

Posteroanterior and lateral chest radiographs show a clear left lung as well as normal heart border and arch. The right side, however, displays nodular pleural thickening with loss of the right hemidiaphragm and possible effusion. The lateral view shows that the disease is primarily affecting the lateral edge of the pleura. Multiple nodular pleural lesions suggest mesothelioma, metastatic disease, and infection.

Axial, contrast-enhanced CT images show subtle, diffuse thickening of the pleura that involves the major fissure. This thickening becomes more prominent in more distal slices (closer to the diaphragm). It is nodular and contiguous with punctate calcifications. T1-weighted MR images confirm the rind of soft tissue thickening in the pleura. There is very little fluid. These findings are characteristic of mesothelioma.

Diagnosis

Discussion

A cross-sectional photo of the extrapleural pneumonectomy specimen shows healthy, uninvolved lung parenchyma. The primary pathologic finding is the marked thickening of the pleura, including involvement of the major fissure; the most pronounced thickening (up to ~2.5 cm) is at the diaphragmatic surface. In addition, there is a focal lesion at the apex. Low power microscopy shows the thickened pleura and uninvolved lung parenchyma. At higher power, the cells themselves appear bland and relatively uniform. The nuclei are vesicular with low mitotic activity; this is a characteristic appearance for epithelial mesothelioma. The suspected diagnosis was confirmed through immunohistochemical analysis. As shown, the sample is positive for cells of mesothelial origin (calretinin stain).

Radiology Discussion:

Although malignant mesothelioma is the most common primary pleural neoplasm, it is relatively rare (1:100,000). In 80% of cases, it is associated with exposure to asbestos; other causes include TB, empyema, and radiation therapy. The most common symptoms include dyspnea, non-pleuritic chest pain, cough, and weight loss. Imaging characteristics include a thickened, irregular mass arising from the pleura that may encase the lung (with associated effusion in 50-75% of cases), visible on radiographs. CT images show circumferential, nodular pleural thickening >1cm (with calcified plaques in 20% of cases), and MR images (though rarely obtained) illustrate pleural thickening that is minimally T1 hyperintense and moderately T2 hyperintense There are a number of different ways to confirm the diagnosis, but needle biopsy is less sensitive than video-assisted thoracoscopic surgery (VATS). The extend of disease is evaluated according to the following five stages:

• IA: Tumor confined to the ipsilateral parietal or diaphragmatic pleura
• IB: Tumor confined to the ipsilateral visceral pleura, lung, or pericardium
• II: Tumor invading the chest wall or mediastinal structures; metastatic spread to thoracic lymph nodes
• III: Tumor extending through the diaphragm to involve the peritoneum; extra-thoracic lymph node metastases
• IV: Distant hematogenous metastases

CT and MR are equally effective for staging, and CT is much more cost-effective.

The preferred treatment for mesothelioma is surgical resection. A tumor of any size can be resected if it is confined to one hemithorax and involves only superficial invasion. Stage I disease is considered to be curable, while stages II and III may benefit from surgery. Treatment of stage I disease is comprised of extrapleural pneumonectomy with resection of parietal and mediastinal pleura, lung, ipsilateral pericardium, and hemidiaphragm. The average length of survival for all patients is 4-12 months; this may be extended to 28 months in post-surgical stage I patients. Mesothelioma is resistant to both chemo- and radiation therapy.

References

BH Miller, ML Rosado-de-Christenson, AC Mason, MV Fleming, CC White, and MJ Krasna. From the archives of the AFIP. Malignant pleural mesothelioma: radiologic-pathologic correlation. Radiographics 1996 16: 613-644.

Williams SC. Thoracic Imaging on the Internet. 2001.

Dahnert WF. Radiology Review Manual, 4th Ed. Lippincott Williams & Wilkins, 1999.

• Return to the Teaching Case Database search page
• Return to Professional Education
  
• About BrighamRAD

Dear Visitors: Nothing on this World Wide Web site should be considered medical advice. Only your own doctor can help you make decisions about your medical care. It is not the policy of the Brigham and Women's Hospital Department of Radiology to provide consultation on the World Wide Web or via e-mail. If you have a specific medical question or are seeking medical care, please call the Brigham and Women's Hospital toll-free physician referral line at 1-800-294-9999.

Is this a mirrored page?
The official homepage of the BrighamRAD Teaching Case Database is http://brighamrad.harvard.edu/education/online/tcd/tcd.html