A Thoracic Mass Discovered at Abdominal Imaging

Abstract

Solitary fibrous tumor of the pleura (SFTP) is a rare primary pleural neoplasm arising from the submesothelial mesenchymal cell layer just beneath the mesothelial lining of the pleura. SFTPs consist of spindle cells embedded within variable amounts of connective tissue, typically staining positive for vimentin and antibodies to CD34. SFTPs are often attached to pleural surfaces through a pedicle. Histopathologic criteria for malignancy include high mitotic counts ( > 4 mitoses per 10 high-power fields), pleomorphism, hypercellularity, tumor giant cells, necrosis, and hemorrhage. Chest radiography in patients with SFTP shows a peripheral mass displaying characteristics suggesting an extraparenchymal location: obtuse angles with the chest wall associated with a circumscribed border on one side of the lesion with an indistinct, "fading" margin on the opposite side of the lesion. Crosssectional imaging findings of SFTP include a variably sized mass contacting the chest wall or the diaphragm, showing enhancement after intravenous contrast administration. Calcification and effusion are uncommon. Magnetic resonance imaging may show decreased T1 and T2 signal, suggesting the fibrous nature of SFTPs, and also typically shows intense, heterogeneous, intravenous contrast enhancement. The treatment of choice for SFTP is wide surgical resection. Key Words: fibrous tumor of pleura, tumor, neoplasm, focal fibrous tumor of the pleura (Clin Pulm Med 2015;22:261-264)T he incidental detection of abnormalities in imaging studies is a common occurrence, not only with thoracic imaging examinations, but at the margins of neck and abdominal crosssectional imaging studies. Many such findings are of no, or at most minor, clinical significance, but occasionally an incidentally detected abnormality is large and compelling enough that its discovery, even for patients with few or no respiratory complaints, mandates immediate further evaluation. The most common incidental abnormalities detected in nonthoracic imaging studies that, by protocol design, necessarily image some of the thorax (such as cross-sectional imaging of the neck or the abdomen) are found within the lungs, but unexpected abnormalities may also be encountered in extraparenchymal locations. Proper localization of the abnormal finding is the key first step to generating appropriate differential considerations and developing an approach to establishing a diagnosis for the patient. CASE REPORTA 66-year-old nonsmoking woman with a history of hypothyroidism on replacement therapy, and a medical history of pancreatitis, presented with complaints of abdominal pain and loose stools beginning over a decade earlier, accompanied by epigastric pain. These complaints were attributed to cholecystitis, for which endoscopic retrograde cholangiopancreatography was performed, but this procedure precipitated an episode of pancreatitis. During the endoscopic retrograde cholangiopancreatography procedure, her common bile duct was found to be narrowed and several stones were extracted, with the plac...