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
Lung Cancer
Bilaterally symmetrical
Associated with asbestos exposure
Histopathalogy shows biphasic pattern
Occurs in late middle age
Bilaterally symmetrical