A Pleural Loose Body Mimicking a Pleural Tumor: A Case Report

Abstract

We present a rare case of a pleural loose body, thought to be a pedunculated pleural tumor, found incidentally in a 58-year-old female. Computed tomography showed a non-enhancing mass, which migrated along the mediastinum and paravertebral area. Thoracoscopic surgery revealed a 4 cm, soap-like mass that was found to be a fibrin body consisting of hyalinized collagen histopathologically. Mobility and the lack of contrast enhancement of a pleural mass are important clues to diagnosing this benign condition.

Keywords: Computed tomography; Loose body; Pleural cavity; Thoracolithiasis.

Fig. 1. 58-year-old woman with pleural fibrin body.

A. Posteroanterior chest radiograph shows right paratracheal mass (arrow). B, C. Pre-contrast CT demonstrates soft-tissue density mass in subcarinal area (arrows). Attenuation of mass was 42-44 Hounsfield units (HU). D, E. On postcontrast CT, mass is observed in right paravertebral area (arrows). Mass did not show contrast enhancement and had attenuation value around 44 HU. F. On preoperative chest radiograph obtained 1 month after initial radiograph, no mass is observed in right paratracheal area. Increased opacity in subcarinal area suggests migration of previous right paratracheal mass to subcarinal area. G. Gross tumor specimen is whitish "soap-like" mass with smooth surface. H. In high-power view, surface of tumor shows scattered chronic inflammatory cells and characteristic "basket-weave" configuration of laminated, hypocellular mature collagen (hematoxylin-eosin stain, × 200 magnification).