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pleural malignancy

Monday 5 January 2015

Differential diagnosis

The role of asbestos exposure in the development of malignant mesothelioma (MM) is well documented. Whereas the classical quartet of chest pain, dyspnea, weight loss, and pleural effusion in a middle-aged or elderly patient with known occupational exposure to asbestos is certainly characteristic of MM, all of these features are nonspecific, and the majority of pleural effusions in patients with asbestos exposure are benign.

Metastatic tumors to the pleura are far more common than primary malignant mesothelioma, and carcinomas of lung, esophagus, stomach, breast, prostate, and thyroid account for most cases.

Metastatic disease from extrathoracic malignant primary tumors is often bilateral, whereas bilateral malignant mesothelioma is unusual in the absence of advanced disease.

Both mesothelioma and metastatic tumors can involve the pleural surfaces diffusely; but metastatic tumors can be localized.

A small percentage of MM forms localized tumors and may be confused with a localized metastasis from an extra-pleural primary or with a primary pleural sarcoma.

Pleural metastases may be the first indicator of clinically silent kidney carcinoma. Metastatic renal cell carcinoma should always be considered in the differential diagnosis of an epithelioid or biphasic pleural malignancy, especially when a clear cell component is present or a CD10 positivity of tumor cells.

Management - Prognosis

Diffuse malignant mesothelioma (MM) is a relentlessly aggressive cancer with limited therapeutic options. Despite aggressive surgical and chemotherapeutic approaches that have been adopted in the treatment of selected patients, the long-term prognosis for the vast majority of patients with malignant mesothelioma remains poor.

As the medical, surgical, psychological, and medico-legal implications of diagnosing malignant mesothelioma are substantial, every effort should be made to exclude atypical reactive processes.

On the other hand, most carcinomas that spread to the pleura share a comparable poor outcome with MM, so that error in this area, although ideally avoided, generally does not substantially impact patient survival.