Clinical description
Mesothelioma has been identified as a disease that occurs in adults; usually surfacing between the age of 50 and 70, with 70-80% instances involving men. Individuals diagnosed in the 20-40 age groups have usually been exposed to asbestos as children. Typical symptoms included chest pain, dyspnoea or both, and in one particular series, one-third of patients had experienced breathlessness without chest pain, due to pleural effusions. Although, the chest pain is usually dull and boring in nature when symptoms manifest, patients can experience a pleuritic-type pain due to pleural effusions. The mediastinal structures are usually involved, but superior vena caval obstruction and hoarseness of the voice do not lead to any major symptoms.
Occurrence of Dysphagia is also possible, albeit this is discovered late. Unlike bronchogenic carcinomas, it is only rare that patients experience lymphadenopathy, haemoptysis, and metastatic symptoms. Although, weight loss, sweating and a chest wall mass are less common symptoms, their involvement may be found during autopsy in up to a third of peritoneal mesothelioma cases. Non-specific symptoms that usually indicate the possibility of peritoneal mesothelioma include nausea, loss of appetite, constipation, diarrhea, vomiting and occasionally ascites. Symptoms such as small bowel obstruction usually manifest in later stages. With a mean survival rate of around 7 months, the prognosis of peritoneal mesothelioma is usually worse in comparison to pleural mesothelioma.
Physical examination has limited use since it can only detect pleural thickening due to tumor infestation and signs of pleural effusion. Finger clubbing has a higher incidence in comparison to other benign asbestos related pleural diseases and is a possibility in up to 30% of cases. The tumor develops mainly on the parietal pleura, after which it starts spreading via the fissures, to eventually encase the lung surfaces. Pericardium infiltration can lead to cardiac tamponade symptoms and mesothelioma can spread along surgical incisions and needle tracks. Blood tests can be used to diagnose an elevated erythrocyte sedimentation rate (ESR). In certain isolated cases, mesothelioma has also been associated with symptoms such as autoimmune haemolytic anaemia.
Diagnosis and differential diagnosis.
For proper diagnosis of mesothelioma, it is essential to use a combination of the patient’s history, physical examination, radiology and prescribed pathological laboratory tests. A careful analysis of the patient’s history is essential with special focus on identifying at-risk occupations that may provide definitive evidence of asbestos exposure. However, the high latency period between exposure and onset of mesothelioma may naturally prevent precise recall of occupational exposure and the work environment that may have existed up to 60 years earlier.
For patients experiencing pleural effusions, the first step utilized in the diagnostic process involves sampling of the fluid for cytological examination. If cells are malignant, the pleural fluid cytology tests turn out positive in around one-third cases. Malignancy of cells can be accepted if radiological, cytological and clinical results also support a mesothelioma diagnosis. However, a pleural biopsy (needle) is also recommended because it is uncommon to make a definitive diagnosis using only the pleural fluid cytology. Performing a contrast enhanced computed tomogram (CT) scan is crucial for ascertaining the spread of the disease and also facilitate a percutaneous biopsy, in case the pleural fluid cytological analysis was found lacking.
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