Teaching Case

A 35-year-old asymptomatic woman was referred for a Chest Radiograph (CR) due to a suspected anomaly found incidentally in a previous CR while abroad.

Contrast-enhanced CT was performed revealing a large and lobulated solid soft-tissue mass, occupying almost two thirds of the right hemithorax, with arterial phase heterogeneous enhancement and progressively more intense centripetal enhancement in the venous phase (Fig. 2). The mass displaced the diaphragm inferiorly and the mediastinum to the left, maintaining strict contact with the latter. Because infiltrative growth into mediastinal structures could not be discarded, MRI was performed (Fig. 3), showing low overall signal in both T1 and T2, suggestive of fibrous component. Diffusion-weighed MRI showed little diffusion restriction, indicative of a probably benign lesion. There were no signs of invasion of mediastinal structures.

Solitary Fibrous Tumours of the Pleura (SFTP) are rare mesenchymal tumours accounting for <5% of all pleural tumours [1], usually discovered incidentally and with generally benign behaviour. Only around 12% are malignant [2].
Around 800 cases of such tumour types have been reported [2].
Affecting males and females equally, the highest incidence is between 60 and 70 years of age [2].
Recent findings have suggested that SFPT may arise from perivascular multipotent mesenchymal elements displaying features akin to pericytes and submesothelial fibroblasts [3].
SFTP most commonly develop in the lower part of the pleural cavity, specifically from the visceral pleura in around 80% [2]. Even though there is no specific size threshold for a SFTP to be considered "giant", existing literature is consistent with this terminology when describing tumours larger than 10cm [2, 4].
Initially they are usually asymptomatic but may cause chest pain, cough and dyspnoea as they grow due to increased pressure on surrounding structures. Rarely may they compress mediastinal structures.
Diagnostic radiology plays an important role in the study of SFTP since many are found incidentally in routine chest radiographs. A CT scan can provide further valuable information regarding the location of SFTP, its relation to surrounding structures, tumour homogeneity/heterogeneity or potential bleeding or necrotic areas [2]. Nevertheless, CT alone cannot differentiate between a benign and a malignant SFTP. As the tumour grows, the likelihood of malignancy also increases, as does its heterogeneity, with increasingly undefined cleavage planes with surrounding structures. MRI or angiography are often performed to evaluate tumour infiltration into mediastinal structures and to evaluate feeding arteries, respectively.
Resection is generally considered curative [2].
Neoadjuvant therapy is not indicated since the biological potential of SFTP is rarely histologically confirmed preoperatively [2]. After tumour resection, in histologically proven tumours adjuvant therapy may be indicated [2].