Introduction

The normal pleura is a thin, barely identifiable soft tissue density lining the inner thoracic cavity on computed tomography (CT) scan. It consists of two layers of serous mesothelial cells with a small amount of pleural fluid in between. The outer parietal layer is attached to the chest wall, and the inner visceral layer covers the lungs, blood vessels, and bronchi. 

Fig. 1: Pleural and extra-pleural anatomy

Although chest radiography is the initial imaging tool for assessment of chest pathology, CT remains the primary modality for the evaluation of pleural mass-like lesions. 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission scan (FDG-PET) is essential in the diagnosis, staging, and management of patients with primary and metastatic pleural tumors.

Classification of pleural lesions

Pleural nodules and masses can be tumoral or tumor-like lesions. Tumoral lesions are divided into metastatic or primary lesions, which can be malignant or benign. Metastatic and primary malignant tumors are more common than benign tumors [1].

A tumor-like condition is any non-neoplastic lesion of the pleura that resembles a tumor and can be either focal or diffuse.

Fig. 2: Classification of pleural lesions.