Extra-pleural space on CT: common lesions and diagnostic approach

Background The extra-pleural space is challenging to view radiologically and is commonly overlooked. Therefore, it is important to have a comprehensive understanding of its anatomy in order to correctly classify lesions as either pleural or extra-pleural so as to choose the most appropriate treatment. CT with multi-planar reformatting allows the assessment of pathological conditions involving the extra-pleural space. The aim of this cross-sectional study was to assess the role of CT in the detection and evaluation of the extra-pleural space lesions and to classify them according to their CT appearance in order to reach a proper diagnosis and successful management plan. Results This study was conducted on 131 patients who underwent CT scan of the chest for different chest complaints, and the detected extra-pleural space abnormalities were classified according to their CT appearance into three major groups which are fatty expansion and soft tissue stranding group that included 59 cases (45%), abnormal attenuation group that included 13 cases (10%), and soft tissue expansion group that included 59 cases (45%). Out of the 59 cases with increased fatty expansion and soft tissue stranding, 73% were of inflammatory cause (either pulmonary or pleural), 17% were of neoplastic cause, and 3 cases were caused by systemic conditions. The abnormal extra-pleural space attenuation group was classified into air-containing and blood-containing groups, and both were mainly caused by trauma. Soft tissue infiltration of extra-pleural space was classified into neoplastic (85%) and non-neoplastic (15%) lesions, while most of the non-neoplastic pathologies were caused by severe inflammatory processes. The axial images were mostly sufficient to detect extra-pleural space lesions. Conclusions CT has a crucial role in the assessment of extra-pleural space and the different lesions involving it. Those lesions can be classified according to their CT appearance in order to reach a proper diagnosis and as a result aid in better management of these pathologies.