IS Case 72: Malignant Mesothelioma

Lisa Siripun, MD

Imaging Sciences URMC 2008
Publication Date: 2009-05-19

History

An 88-year-old female presents with dyspnea.

Discussion

Malignant mesothelioma is the most common primary pleural neoplasm associated with asbestos exposure. The patient usually presents with dyspnea, chest pain, cough and weight loss. As the disease progresses, it often extends into the pulmonary parenchyma, chest wall, mediastinum and diaphragm. It is almost always fatal with median survival of 11 months. Factors associated with a reduced survival time include intrathoracic lymph node metastases, distant metastases, and extensive pleural involvement. Butchart Staging for Malignant Mesothelioma:

Stage Findings

  1. Tumor confined to the ipsilateral pleura, lung, or pericardium
  2. Tumor invading the chest wall or mediastinal structures, or metastasis to thoracic lymph nodes
  3. Tumor extending through the diaphragm to involve the peritoneum or extra-thoracic lymph node metastasis
  4. Distant hematogenous metastasis

On chest radiograph, the lesion usually appears as a markedly thickened, nodular, irregular pleural based mass which coats the pleural surface and grows along fissures. The tumor often encircles the involved lung and is only rarely bilateral. Chest wall, diaphragmatic, and mediastinal invasion can be seen with more advanced disease. A moderate to large ipsilateral pleural effusion is seen. Because mesothelioma encases the lung, it may fix the affected hemithorax so there may not be mediastinal shift of the contralateral hemithorax, in fact there may be evidence of volume loss on the affected side even in the presence of massive effusion.

Common findings on CT include a unilateral pleural effusion, nodular pleural thickening, and interlobar fissure thickening. Mediastinal pleural involvement is also seen. The absence of pleural thickening does not exclude malignancy. Irregularity of the interface between the chest wall and the tumor is not a reliable indicator of chest wall invasion. Transdiaphragmatic extension include a soft tissue mass invading the hemidiaphragm, while a clear fat plane between the diaphragm and adjacent abdominal organs and a smooth diaphragmatic contour indicate the tumor is confined to the thorax.

Diagnosis is made based on thoracoscopically-guided biopsy. Treatment includes surgical resection for limited disease, radiation therapy, and chemotherapy.

References

  1. Dee EK, Garg K. Mesothelioma, malignant. E-medicine. August 15, 2007. http://www.emedicine.com/radio/topic449.htm
  2. Tan WW, Weiss G. Mesothelioma. E-medicine. February 9, 2007. http://www.emedicine.com/med/topic1457.htm

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