Mesothelioma – Top USMLE Diseases

Malignant mesothelioma (usually referred to as simply "mesothelioma") is the malignant growth of mesothelial cells, most commonly affecting the pleura. The majority of cases are associated with occupational exposure to asbestos that occurred > 20 years before clinical onset, which includes dyspnea, chest pain, coughing, fatigue, and weight loss. Chest computed tomography (CT) scan shows multifocal pleural thickening and pleural effusion. Pleural biopsy is required for confirmation and to rule out metastases from lung or breast cancer. Treatment is rarely effective, with an average survival time of < 1 year.

Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. To perform this function, the lungs need to be able to capture as much O2 as possible, a task that is easily achieved owing to their elastic morphology. Each lung is enclosed within the visceral pleura and completely fills 1 of the non-symmetrical pleural cavities, which are situated on the left and right sides of the mediastinum. The lungs encase the bronchial tree and are divided functionally and anatomically into lobes.

Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Molecular profiling of the cancer provides further distinction of the tumor's biological behavior, prognosis, and treatment options. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Regional and metastatic spread cause additional symptoms and complications depending on the location and organ(s) affected. Related paraneoplastic syndromes include hypercalcemia, hyponatremia, Lambert-Eaton syndrome, Cushing's syndrome, polydermatomyositis, and dermatomyositis. Definitive diagnosis and staging are made by biopsy, genetic mutation with biomarker testing, and imaging. Management is guided by the cancer stage and associated molecular profile. Lung cancer carries an overall poor prognosis.