Pleural mass is mainly seen in primary or metastatic pleural tumors. Primary tumors are mostly pleural mesothelioma, but also fibroma, leiomyoma, and neurofibroma from connective tissue. Pleural tumor can be localized or diffuse, and diffuse tumors are all malignant. Pleural effusion may be present. Masses accompanied by pleural effusion are mostly malignant. In addition, pleural mass can also be seen in pleural plaques formed by organizing empyema and asbestosis.
X-ray
On chest x-ray film, pleural mass is manifested by homogeneous, sharply marginated, hemispherical, lenticular, or irregular dense opacity intersecting with the chest wall at an obtuse angle. Diffuse mesothelioma may be accompanied by pleural effusion, and metastatic tumors may be accompanied by rib destruction.
Figure 1 Pleural tumor
a. Chest plain film shows lenticular opacity of soft tissue density at the left apical lung (↗); b. CT mediastinal window shows lenticular opacity of soft tissue density protruding from the left chest wall into the lung (↗).
CT
CT shows massive opacity of soft tissue density connected to the chest wall with broad base. Sometimes the periphery of the mass extends to the pleura, forming pleural tail sign. On contrast-enhanced CT, mass often has obvious enhancement. Diffuse pleural tumors often present generalized pleural thickening, with rough inner edges, are nodular or wavy, and may involve the entire pleura on one side. Pleural plaques of organizing empyema or asbestosis are often accompanied by calcification.
MRI
Pleural mass is isointense on T1WI and hyperintense on T2WI.