To identify computed tomography (CT) predictors of malignancy, from a retrospective study of preoperative CT scans of patients with solitary fibrous tumors (SFT) of the pleura.

The CT scans of 56 patients with histopathologically confirmed SFT (33 women and 23 men; mean age, 60years) who underwent surgery between December 2004 and November 2012 were retrospectively analyzed by three radiologists working in consensus, blinded to the final histological diagnosis.

SFT was asymptomatic and incidentally discovered in 22 patients (45.8%). Resection specimen analysis (R0 resection in all cases) revealed that 23 tumors (41%) were malignant. The CT features, which significantly differed between malignant and benign SFTs were tumor size (P=0.002) with a discriminative threshold value of 10cm, tumor heterogeneity before (P=0.02) and after (P=0.03) intravenous administration of iodinated contrast material, presence of intratumoral hydric attenuation areas (P=0.01), pleural effusion (P=0.01), measurable intratumoral vessels (P=0.02), hypervascularization with visible intratumoral vessels and/or marked enhancement (P=0.001). Presence of intratumoral calcifications (P=0.2) and maximum post-contrast enhancement value (P=0.6) were not significantly different between the two groups.

A size greater than or equal to 10cm, hypervascularization, attenuation heterogeneity and association with pleural effusion are individual variables that suggest malignant SFT on CT.