A Slowly Growing Extraparenchymal Mass: Imaging Considerations

Abstract

Solitary fibrous tumor of the pleura (SFTP) is a rare primary pleural neoplasm that most commonly arises from visceral pleural surfaces. SFTPs consist of spindle cells embedded within variable amounts of connective tissue, and may stain positive for vimentin and antibodies to CD 34. Grossly, SFTPs often are attached to pleural surfaces via a pedicle. Most SFTPs are benign, although malignant degeneration may occur in approximately 40% of lesions. Histopathologically, malignancy is favored when high mitotic counts (greater than 4 -10 per high power fields), pleomorphism, high cellularity with crowding and overlapping nuclei, tumor giant cells, necrosis, and hemorrhage are encountered. Chest radiography may show a peripheral mass that may show characteristics suggestive of an extraparenchymal location: obtuse angles with the chest wall associated with a circumscribed border on one side of the lesion and a fading margin on the other side. Cross sectional imaging findings of SFTP include a variable sized mass in contact with the chest wall or diaphragm that shows enhancement following intravenous contrast administration. Calcification and effusion are uncommon. Magnetic resonance imaging may show decreased T1 and T2 signal, consistent with the fibrous nature of the lesion. The treatment of choice for SFTP is wide surgical resection.