Solitary fibrous tumor of the pleura: a rare cause of elevation of the right lung base

Abstract

A 42-year-old female nonsmoker with no history of comorbidities was admitted to the hospital with a 6-month history of right-sided chest pain and dyspnea. A chest X-ray showed marked elevation of the right lung base (Figures 1A and 1B). Laboratory test results were unremarkable. A magnetic resonance imaging scan of the chest revealed a heterogeneous mass in the right hemithorax, with intermediate signal intensity on T1and T2-weighted images (Figures 1C and 1D). A transthoracic needle biopsy was performed, and the results were inconclusive. The patient underwent radical surgical resection by open thoracotomy. The tumor was pedunculated, with free margins, measuring approximately 12 × 11 × 6 cm, and the pedicle was connected to the mediastinal pleura. The final diagnosis was solitary fibrous tumor of the pleura (SFTP). The postoperative evolution was uneventful. Elevation of the right lung base may occur associated with elevation of the right hemidiaphragm or with the diaphragm in normal position. In the first condition, the main causes are phrenic paralysis(1) and the presence of an expansive lesion (e.g., a hepatic tumor or a subphrenic abscess) below the diaphragm. In the second condition, the main cause is infrapulmonary pleural effusion, although other, uncommon, causes include pleural tumors, such as SFTP. A solitary fibrous tumor is defined as a mesenchymal neoplasm that has fibroblastic characteristics and clear peripheral vascular tumor-like branching vascularization. Although such tumors most commonly affect the pleura, they can occur in other thoracic areas (i.e., the mediastinum, pericardium, and lung), as well as in extrathoracic areas (i.e., the abdomen, head/neck, and central nervous system).(2-4) An SFTP is often asymptomatic and discovered incidentally by radiography performed for other reasons. When signs and symptoms (including digital clubbing and hypertrophic osteoarthropathy) are present, they are usually associated with larger tumors. Patients with SFTP occasionally have hypoglycemia, which is seen more often in patients with malignant SFTP and is known as DoegePotter syndrome. Doege-Potter syndrome is believed to be a type of non-insulin-dependent hypoglycemia.(2,3) Computed tomography (CT) of a small SFTP frequently demonstrates a homogeneous, well-defined, noninvasive, lobular soft-tissue mass, usually adjacent to the chest wall or within a fissure. Larger lesions are typically heterogeneous and may not exhibit CT features suggestive of focal pleural tumors.(4) Heterogeneous areas of low attenuation on unenhanced CT scans may be caused by hemorrhage, necrosis, or cystic changes.(3,4) Changes in tumor location can be detected and are often related to the attachment of a benign SFTP to the pleural tissue through the pedicle.(3) Most localized fibrous tumors arise from the visceral pleura, and nearly half are pedunculated, the vascular supply to the tumor being contained within the pedicle.(4)