All of the following sire true regarding mesothelioma except:

Ans. a. Bilaterally symmetrical Malignant Mesothelioma is multicentric tumor with multiple pleura-based nodules coalescing to form sheets of tumor (but not bilaterally symmetrical).Malignant Mesothelioma* Malignant mesothelioma is MC tumor of the pleura* In 20% of malignant mesotheliomas, the tumor arises from peritoneum* Exposure to asbestos is the major known risk factor* More common in males, most common after 40 years of age.* Three types: Epithelial, sarcomatous, and biphasicQ* Epithelial types are associated with a more favorable prognosis1*Pathophysiology:Physical characteristics of specific fibers (referred to as serpentine or amphibole) have been shown to be important.* Serpentine fibers: Large and curly, not able to travel beyond larger airways.* Straight amphibole fibers: In particular the crocidolite** fibers navigate distally into the pulmonary parenchyma, most clearly associated with mesotheliomas.* Latency period between asbestos exposure and the development of mesothelioma is at least 20 years.* Multicentric tumor with multiple pleura-based nodules coalescing to form sheets of tumor (but not bilaterally symmetrical)* Natural history of the disease in untreated patients culminates in death due to local extension.Malignant MesotheliomaClinical Features:* Most patients present with dyspnea and chest pain.* Over 90% have a pleural effusionQ.Diagnosis:Results of thoracentesis are diagnostic in <10% of patients.Chest X-ray: Pleural effusion, generalized pleural thickening and shrunken hemithorax.Thoracoscopy or open pleural biopsy with special staining of tumor samples is required to differentiate mesotheliomas from adenocarcinomas9.Management:* No effective therapy* Treatment options: Supportive care only, surgical resection, and multimodahty approaches (using a combination of surgery', chemotherapy, and radiation therapy).Differentiation of Mesothelioma from Adenocarcinoma MesothetiomaAdenocarcinomaCEANegativePositiveVimentinPositiveNegativeLow molecular weight cytokeratinsPositiveNegativeElectron microscopic featuresLong, sinuous villiShort, straight villi with fuzzy glycocalyx