In 13 (72.2%) cases tumour was in the right pleural cavity. In two cases pleural tumours were bilateral, the other case being left sided. The site of one tumour was unknown. Tumour invariably encompassed the pleural cavity with extension along the interlobar fissures, infiltrating the underlying lung parenchyma and affecting the mediastinal structures including the pericardium. Spread to the chest wall was also common. The tumour varied from 0.5 cm to many centimetres in thickness. The underlying lung was often atelectatic.