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Q1: What does the initial radiograph show (see p 243)?
The initial radiograph shows a homogenous opacity the left hemithorax with a concave upper border, slightly higher laterally, and obscuring the diaphragm and underlying lung.
Q2: What does the radiograph after the chest drain demonstrate (see p243)?
There is marked pleural thickening on the lateral borders of the left hemithorax.
Q3: What is its significance?
Pleural thickening can be due to previous pulmonary infection, infarction, lipoma, lymphoma, tumour, or previous asbestos exposure. More extensive unilateral pleural thickening is usually the result of tuberculous pleuritis, mesothelioma, previous thoracotomy, or pleural effusion.
Q4: What is shown on the chest photograph (see p243)?
There is small round to oval lump in the region of chest drain.
Q5: What is the unifying diagnosis?
Mesothelioma may affect pleura, peritoneum or pericardium, the last two sites being less commonly affected than pleura. Malignant mesothelioma is usually due to prolonged exposure to asbestos dust, particularly croccidolite. The tumour characteristically affects 20–40 years after exposure to asbestos. The first symptoms are those associated with worsening dyspnoea, pleural effusions, chest pain, and weight loss. The usual appearance is nodular pleural thickening around all or part of lung. A haemorrhagic pleural effusion may be present but the lung changes of asbestos may be absent. The effusion may obscure the pleural masses. Often the mediastinum is central despite the presence of a large effusion, and this is thought to result from volume loss of the underlying lung secondary to either ventilatory restriction by the surrounding tumour, or bronchial stenosis by tumour compression at the hilum.1 Rib involvement may occur with malignant mesothelioma. In the advanced stages of disease, patients will gradually become weaker and cachectic as the tumour bulk increases. Eventually, they will develop unremitting chest pain secondary to the invasion of the chest wall and intercostal nerves. Dyspnoea will worsen due to restriction of lung and chest expansion. Palpable tumour masses may be present at this stage.
Differential diagnosis includes tuberculous pleural disease and secondary pleural carcinoma, the later usually bilateral except when due to bronchial or breast carcinoma.
Histology alone cannot differentiate malignant mesothelioma from other pleural cancers and further immunohistochemistry and or electron microscopy are mainstays of definitive diagnosis. If the diagnosis cannot be made from examination of pleural fluid and if the needle biopsy specimen was insufficient, under these circumstances, evidence of pleural tumour, consistent with the diagnosis is sufficient to exclude a treatable cause of pleural disease and is also adequate evidence in UK for industrial injuries benefit to be paid.2 The trimodality therapy, consisting of an extrapleural pneumonectomy, 4–6 week cycles of chemotherapy, and radiation therapy, has the best results for palliation and longer disease-free survival.
Occasionally malignant mesothelioma is complicated by tumour seeding along biopsy or drainage tracts. It has been suggested that one should avoid repeating such procedures in patients with suspected mesothelioma.3
The occurrence of such skin deposits however, appears to have little clinical consequence because they are not painful and cause no other morbidity.4
Death usually occurs in 4–12 months due to complications of pneumonia or respiratory failure.3