A solitary fibrous tumor arising in the parapharyngeal space, with MRI and FDG-PET findings.

We present the imaging and pathological features of a 38-year-old man in whom a large parapharyngeal solitary fibrous tumor (SFT) on the left side was found. On MRI, the tumor showed a nodule-in-nodule appearance. The inner nodule revealed high signal intensities both on T1- and T2-weighted MR images. The entire tumor showed heterogeneous enhancement on gadolinium-enhanced T1-weighted images. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) identified heterogeneous radiotracer uptake of FDG in the inner nodule of the tumor. Histologic examinations revealed an admixture of growth patterns, including a "patternless pattern" and "haemangiopericytoma-like pattern". The tumor was positive for CD34. Imaging features of SFT arising in the parapharyngeal space are discussed with a review of literatures. This is the first report of FDG-PET finding of SFT arising in the head and neck. More cases are needed to achieve diagnostic significance from FDG-PET findings of parapharyngeal SFTs.