The differential for a single pleural mass is essentially the same as that for multiple pleural masses with the addition of a few entities.
- tumors
- pleural tumors
- metastatic pleural disease, particularly from adenocarcinomas, e.g.
- lymphoma: pleural lymphoma
- invasive thymoma
- lipoma
- loculated fluid (on plain film)
- mass related to ribs or chest wall, e.g. Ewing sarcoma of chest wall, Askin tumor
- mass related to the intercostal nerve
- splenosis - thoracic splenosis
- infection including tuberculosis