Focal pleural tumorlike conditions: nodules and masses beyond mesotheliomas and metastasis

A tumorlike condition of the pleura is any nonmalignant lesion of the pleura or within the pleural space that could be confused with a pleural tumor on initial imaging. Tumorlike conditions of the pleura are relatively rare compared with neoplastic lesions such as mesotheliomas and metastases. Imaging-based diagnosis of these conditions can be difficult due to the similarity of appearance. Thus, recognition of certain imaging patterns and interpretation of these patterns in the clinical context are important. Pleural endometriosis, thoracic splenosis, thoracolithiasis, foreign bodies, pleural pseudotumors and pleural plaques are significant examples of focal tumorlike conditions discussed in this article. Computed tomography is the mainstay imaging technique for the primary assessment of pleural disease, but other imaging methods, such as magnetic resonance imaging and positron-emission tomography, can be of great support in the diagnosis.