Case Introduction: An unusual clinical feature of mesothelioma is the presentation of Contralateral Mediastinal Shift due to pleural mesothelioma tissue, rather than a pleural effusion.

Case Summary: A woman, 63 years of age, who had been treated in the past for invasive ductal carcinoma of the breast, presented with chest pain and breathlessness. A radiograph of the chest revealed that she had contralateral Mediastinal Shift. Her symptoms were relieved after drainage of over 3 litres of pleural fluid.

Further investigations that she underwent revealed pleural mesothelioma rather than metastatic breast cancer which was expected. A few months later she again re-presented with breathlessness and a Contralateral Mediastinal shift was also again demonstrated in a chest radiograph.

On this occasion, a thoracic ultrasound revealed only a small loculated pleural effusion and, surprisingly, a large amount of malignant tissue which explained what was appearing in the chest radiographs.

Case Conclusion: This case illustrates that the mesothelioma tissue itself caused the mediastinal shift away from the affected side, not a pleural effusion which usually causes contralateral mediastinal shift in mesothelioma cases.