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Essentials of Diagnosis

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  • • Associated with asbestos exposure.
  • • Nonexertional chest pain and dyspnea are presenting symptoms.
  • • Pleural effusion is common.
  • • Pleural thickening and/or nodules are present on chest computed tomography (CT).
  • • Thoracoscopy or thoracotomy is often required for definitive diagnosis.

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General Considerations

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Malignant pleural mesothelioma (MPM) is a rare tumor with only 2000–3000 new cases each year in the United States. MPM is strongly associated with asbestos exposure, which can be documented in up to 80% of cases. Thus, workers with heavy industrial exposure to asbestos, such as pipe fitters, naval yard workers, plumbers, welders, and asbestos factory workers, have a remarkably higher risk of developing MPM than the general population. Asbestos fibers are found more frequently and in larger concentrations in the lung parenchyma of patients with MPM than in the general population. Animal studies also corroborate a role of asbestos in the pathogenesis of MPM.

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Recent interest has focused on a potential role of simian virus 40 (SV40) in the etiology of this malignancy. Several lines of preclinical research support this hypothesis such as the presence of SV40 sequences in MPM tumors. It has been suggested that SV40 may interact with asbestos fibers to induce MPM. This issue is controversial, but provides a basis for investigational approaches to management of MPM such as vaccine therapy against the SV40 tumor antigen.

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MPM is generally a disease of advanced age. The median age is approximately 60, consistent with prolonged latency between asbestos exposure and clinical manifestation of disease, which is typically two to five decades. The male:female ratio is 4–5:1.

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There are three main pathological subtypes: epithelial, sarcomatoid, and mixed histology. The sarcomatoid variant is relatively uncommon and has the worst prognosis. The epithelial subtype is associated with better survival.

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As described below, management of MPM has largely been characterized by pessimism, but recent developments have provided an increasing number of treatment options.

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Clinical Findings

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Symptoms and Signs

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Nonexertional, nonpleuritic chest pain and/or dyspnea are the presenting symptoms in 90% of patients. These symptoms typically wax and wane but do not resolve. Over time MPM encases the lung and progressively invades the chest wall, leading to worsening dyspnea and constant pain. Other symptoms include cough, weight loss, and fever. Spontaneous pneumothorax is occasionally the presenting symptom of the disease.

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Physical examination typically demonstrates decreased breath sounds and associated dullness to percussion in areas of marked pleural thickening and/or pleural effusion. A chest wall mass may be evident late in the course of the disease.

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Laboratory Findings

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There are no specific laboratory findings that are diagnostic for MPM, but mild thrombocytosis and anemia are common.

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Imaging Studies

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Chest radiographs reveal a pleural effusion ...

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