CASE 5997 Published on 24.02.2008

Localized fibrous tumor of the pleura mimicking a pleural effusion

Section

Chest imaging

Case Type

Clinical Cases

Authors

Santana Garcia, Maria Angeles; Rodriguez Delgado, Luisa Elena; Pascual Perez, Sonia; Gómez Ferrera, Nayra; Alventosa Fernandez, Elena; Gonzalez Gonzalez, Maria Candelaria; Bello Baez, Adan; Fuentes Alvarez, Julio.

Patient

70 years, female

Clinical History
A 70-year-old women presented to the Emergency Room with complaints of left sided chest pain with exacerbation during inspiration, dyspnoea and palpitations. She reported dry cough for three weeks, without fever.
Imaging Findings
Past History: Three years ago, the patient had undergone mechanical mitral valve replacement and she was under anticoagulant treatment. Physical examination: dullness to percussion, with absent breath sounds over the left hemithorax. A posteroanterior and lateral Chest radiograph (figure 1) on admission to the hospital showed homogeneous and well-circumscribed opacification occupying the lower two-thirds of the left hemithorax. The initial diagnosis of pleural effusion was made, and a difficult pleurocentesis yielded a little amount (20 ml) of bloody fluid. Then, a chest CT (figure 2 ) was performed and the initial diagnosis was modified at that moment, according to the CT findings. The interest of this case is the presentation of this Solitary Fibrous Tumour. In the emergency room the patient was diagnosed of pleural effusion according to the symptoms, physical examination, chest x-ray and CT. The diagnosis of a septated pleural effusion was made by a non-experienced radiology resident on guard. Next day several experienced radiologists found clues for a different diagnosis: CT showed branching linear structures of enhancement within the lesion –consistent with intralesional blood vessels (figure 3)- and the CT numbers were similar to those of soft-tissue attenuation. Then, the possibility of a pleural tumour was taken into account. After a diagnostic pleuroscopy, the patient underwent a thoracotomy, and a large lobulated gray-white mass with firm consistency occupying a great portion of the left hemithorax was encountered. The histologic diagnosis was of localized fibrous tumor of the pleura.
Discussion
Localized fibrous tumors are rare mesenchymal neoplasms that most commonly affect the pleura but have also been described in a number of other locations including the mediastinum and the lung. Extrathoracic localized fibrous tumors have been reported in the abdomen, the head and neck, and the central nervous system. Localized fibrous tumors of the pleura (LFTP), also known as benign mesotheliomas, localized fibrous mesotheliomas, and pleural fibromas, are rare tumors, accounting for less than 5% of all neoplasms involving the pleura. These tumors originate from submesoepithelial mesenchymal cells, and approximately 80% arise from the visceral pleura. They are not related to asbestos exposure. Although the most common primary pleural neoplasm is malignant mesothelioma, radiologists should also be able to identify the much rarer LFTP, as these two neoplasms have radically different prognoses. These tumors, commonly found in the dependent portions of the thorax, may range from 1 to 39 cm in diameter. Large tumors usually displace rather than invade adjacent structures. Because of the presence of a vascular pedicle in 30-50% of patients, these tumors may show a change in shape and location with changes in respiration or position. Benign and malignant subtypes of LFTP are recognized. On unenhanced CT scans, localized fibrous tumors show soft-tissue attenuation. MR imaging typically demonstrates intrathoracic lobular masses of heterogeneous signal intensity with both T1- and T2-weighted sequences. Internal low-signal-intensity septa on T2-weighted images are common. On CT and MR images, marked enhancement caused by the rich vascularization is usually seen with the administration of IV contrast material. CT and MR images may show associated, regions of hemorrhage and necrosis, tumoral calcifications and pleural effusions. Rib erosion is rare. Although approximately half the patients with localized fibrous tumors of the pleura are asymptomatic, cough, chest pain, and dyspnea may be presenting symptoms, especially in patients with large tumors. Hypertrophic osteoarthropathy is seen in 4-35% of patients, and hypoglycemia is noted in up to 5%. Atelectasis of the adjacent lung and mass effect on the mediastinum are common associated findings. The fibrous acellular nature of localized fibrous tumors makes diagnosis by transthoracic needle biopsy difficult. Although there are no imaging features that definitively distinguish benign from malignant subtypes of LFTP, heterogeneity on cross-sectional images, mass effect, and pleural effusion may be slightly more common in malignant lesions.
Differential Diagnosis List
Localized fibrous tumor of the pleura
Final Diagnosis
Localized fibrous tumor of the pleura
Case information
URL: https://www.eurorad.org/case/5997
DOI: 10.1594/EURORAD/CASE.5997
ISSN: 1563-4086