Solitary fibrous tumours in the extracranial head and neck region: correlation of CT and MR features with pathologic findings

Solitary fibrous tumours (SFTs) are rare, mesenchymal neoplasms. The purpose of this study was to analyse the radiological and clinicopathological features of SFTs in the extracranial head and neck region. We retrospectively reviewed the clinical, computed tomography (CT), magnetic resonance imaging (MRI), and pathological features in 18 patients (12 men and 6 women), aged 18-75 years, with histologically proven SFTs in the extracranial head and neck region. Fourteen patients underwent CT scanning and nine underwent MRI. The histological techniques included routine haematoxylin-eosin staining and immunohistochemical analysis. Clinical data were retrieved from the medical records. Most tumours presented as a slow-growing painless mass. Eighteen SFTs arose in the orbit, cheek, masticator space, the parapharyngeal space, infratemporal fossa, maxillary, submandibular space and the parotid gland, respectively. All 18 lesions were found as a solitary mass, ranging in size from 1.2 to 6.8 cm (mean 3.57 cm). They mostly presented with an ovoid shape, with well-defined margin, and isodensity on plain CT, isointensity on T1-weighted imaging, mild hyperintensity on T2-weighted imaging and diffusion-weighted imaging, and marked heterogeneous enhancement on contrast-enhanced CT and MRI. The time-intensity curves (TICs) exhibited a rapidly enhancing and slow washout pattern on dynamic contrast-enhanced MRI and dual-phase CT. Imaging findings of the SFTs depended on the histopathological components. SFTs most commonly present with an asymptomatic mass in adults. A solitary, ovoid and well-defined mass with strong enhancement after contrast agent injection is suggestive of this diagnosis. Rapidly enhancing and slow washout pattern TICs may be additional valuable features.