Variable Solitary Fibrous Tumor Locations: CT and MR Imaging Features

Abstract

The aim of the study is to describe the radiological imaging features of different solitary fibrous tumors (SFTs) locations and present histopathological correlations. From 2007 to 2013, 20 cases of histologically confirmed that SFTs were retrospectively analyzed with computed tomography (CT; 9/20), magnetic resonance imaging (MRI; 5/20), or both CT and MRI (6/20). All 20 SFTs were well defined, lobular, soft-tissue masses, and 60% were located outside of the pleura. One pleural case invaded to the 10th thoracic vertebra and had lung metastases. Images revealed 11 heterogeneous lesions that exceeded 3.0 ± 0.203 cm along the greatest axis with patchy necrotic foci, and 9 homogeneous lesions <3.0 ± 0.203. Microscopically, all SFTs were proliferative spindle cells with varying degrees of fibrosis and interspersed vessel branching. Cells were strongly immunopositive for CD34. Here we review variable imaging findings of SFTs, which can be within the pleura as well as within other serosal tissues such as the meninges and postperitoneum. SFTs > 3.0 ± 0.203 cm along the greatest axis appeared to be mixed patterns, whereas SFTs < 3.0 ± 0.203 cm had isodense appearances. SFTs cells were CD34 immunopositive and surgery was a first-line treatment choice.

FIGURE 1

Receiver operating characteristic (ROC) curve. The SFTs imaging features were classified with homogeneous and heterogeneous enhancement. The ROC curve showed in 3.0 ± 0.203 cm of the tumor great size; the homogeneous and heterogeneous enhancement sensitivity and specificity were 0.95, respectively. ROC = receiver operating characteristic.

FIGURE 2

Typical features of larger SFTs. A, A’: A 35-year-old man with an incidental finding of SFT. Parenchymal (A) and mediastinal (A’) contrast material-enhanced CT images showed a round solitary fibrous tumor of the pleura. B, B’: A 54-year-old male presented with a pelvic SFT. Contrast-enhanced CT image (B, axial) and (B’ coronal) views reveal an oval, well-defined heterogeneous mass with patchy hyperdense (tumor tissue, arrow) and hypodense (necrotic tissue, curved arrow) areas and marked heterogeneous enhancement. C, C’: A 41-year-old female patient with a brain SFT. MR T2-weighted images revealed a heterogeneous hypo- and hyperintense mass in the occipital lobe (C). Contrast-enhanced T1-weighted images showed heterogeneous enhancement of the lesion (C’). CT = computed tomography, MR = magnetic resonance, SFTs = solitary fibrous tumors.

FIGURE 3

Typical features of small SFTs. A, A’: A 43-year-old man with parenchymal (A) and mediastinal windows (A’) of the CT scan showed a round solitary fibrous tumor of the pleura (≤2.8 × 2.3 cm). B, B’: A 48-year-old female patient presented with a right kidney solitary fibrous tumor. Arterial (B) and portovenous (B’) phases of contrast-enhanced CT showed a spherical, well-defined homogeneous mass with marked homogeneous enhancement. C, C’: A 68-year-old female patient with brain SFT. A T1-weighted axial MRI scan revealed a large lobulated hypointense mass (arrow) in the left cerebellum (C). Gadolinium-enhanced T1-weighted axial MRI (C’) showed marked and homogeneous enhancement of the mass (arrow). CT = computed tomography, MRI = magnetic resonance imaging, SFTs = solitary fibrous tumors.

FIGURE 4

Typical features of malignant SFTs. A mass was found that originated from the pleura and was metastasized to the lung. CT mediastinal windows (A) showed a homogeneous lesion (curved arrow) in the left pleura invading to the neighboring T10 vertebral body (arrow, confirmed pathology). Parenchymal windows (B) showed metastases (arrows) in the right lung. Lesions (arrows) are marked and heterogeneously enhanced on T1-weighted MRI scans (C and D). CT = computed tomography, MRI = magnetic resonance imaging, SFTs = solitary fibrous tumors.

FIGURE 5

Typical features of rare locations of SFTs. A, A’: A 71-year-old man with a pancreatic SFT. Contrast-enhanced CT showed an oval, well-defined heterogeneous mass (arrows) with marked heterogeneous enhancement (A, A’). B, B’: A 69-year-old man with an esophageal SFT. CT images before (B) and after (B’) contrast-enhancement showed an oval, well-defined homogeneous mass with marked homogeneous enhancement (arrow). C, C’: A 57-year-old male patient with an orbital SFT. T1-weighted MRI scans before (C) and after (C’) contrast-enhancement showed an oval, well-defined heterogeneous mass (arrow) with marked heterogeneous enhancement. CT = computed tomography, MRI = magnetic resonance imaging, SFTs = solitary fibrous tumors.

FIGURE 6

Histopathological views of SFTs. (A) Histomicrograph (H&E 200×) showed that the SFT was composed of a patternless proliferation of spindle cells with varying degrees of fibrosis. (B) A histomicrograph (200×) depicts extensive immunopositive CD34 expression. SFTs = solitary fibrous tumors.