Solitary fibrous tumour of the pleura

Clinical History

A 45-year-old man with no relevant medical history was admitted to our hospital to have a medical check up. In the routine posteroanterior and lateral chest radiographs (RX), an incidental opacity in the left lung was discovered.

Imaging Findings

Posteroanterior and lateral chest radiographs show an extrapaulmonary, well defined, solid mass in the lower third of the left lung (Fig. 1). No other abnormalities were seen.
Chest CT with intravenous contrast medium administration was performed to characterise the incidentally discovered mass (Fig. 2). A little enhancing (50 UH, similar to adjacent muscle), heterogeneous, solid, well-circumscribed lobulated mass with a broad base to the left posterior pleura was discovered. The extrapleural fat was largely respected and adjacent bones were not compromised. The imaging findings were consistent with an extrapulmonary location of the mass.
Ultrasound-guided biopsy was subsquently performed and histological results were compatible with a solitary fibrous tumour of the pleura.
Surgical removal of the mass (Fig. 3, 4) was performed and confirmed the diagnosis.

Discussion

Solitary fibrous tumour of the pleura (SFTP) is a rare tumour which originates from the mesenchymal cells below the mesothelial lining of the pleura, being the visceral pleura the most affected. SFTP is usually histologically benign. It appears between the sixth and seventh decades of life, with no sex preference and it hasn't`t been shown to be related to asbestos exposure [1] .
About 50% of the patients with SFTP are asymptomatic and the lesion is discovered as an incidental finding. However, patients may present cough, chest pain, dyspnea, haemoptysis or fever. Sometimes, para-neoplastic syndromes such as hypertrophic pulmonary osteoarthropathy or severe symptomatic hypoglycemia (4% of patients) may be found [2, 3].
On plain chest radiogrpah, SFTPs appear as well-circumscribed, extraparenchymal, solid masses. They could be round or lobed, stalked or sessile and they may associate pleural effusion [4]. Chest CT with intravenous contrast is the imaging modality of choice to diagnose SFTP. Iodinated contrast is used to differentiate between benign and malignant disease, to establish local invasion and to confirm the solid nature of the tumor. CT findings may be important for a working-up diagnosis in patients with poor performance status who do not accept, or are unfit for, invasive biopsy procedures [1, 5]. They usually appear as well-circumscribed, slight enhancing, homogeneous solid masses which sometimes present tiny calcifications [1]. Benign SFTPs spare extrapleural fat in their growth and they don't affect or erode adjacent bone structures. Malignant pleural mesothelioma and pleural metastases are the most important malignant tumours which must be excluded [4].The first one is associated to asbestos exposure. Pleural metastases are the most common cause of malignant pleural mass, and sometimes it is impossible to differentiate them from SFTPs [6]. The biopsy before resection is an important initial step in the differential diagnosis [3], and it is doesn't seem to be associated with spread of the tumor [3]. The recurrence after biopsy is rare [7]. Other benign entities as encapsulated pleural effusion have been reported in the differential diagnosis of SFTPs [3]. The most practical approach is to evaluate serial radiographs, as the liquid collections can vary rapidly (vanishing tumour), whereas SFTPs will always have the same size and shape [4].
Complete surgical resection is usually required, although conservative treatment is possible in small lesions [6]. Recurrence of the tumour is infrequent (approximately 2% for pedunculated and 8% for sessile tumours) [3].

Differential Diagnosis List

Final Diagnosis

Solitary fibrous tumour of the pleura.

URL:	https://www.eurorad.org/case/9819
DOI:	10.1594/EURORAD/CASE.9819
ISSN:	1563-4086