Abstract
Solitary fibrous tumor is a rare spindle-cell neoplasm of mesenchymal origin. In head and neck region, the tumors present slow-growing masses, often with local compressive symptoms. Although it is generally benign, malignant variants have been identified. The radiological diagnosis of solitary fibrous tumor is usually based on computer tomography and/or magnetic resonance imaging. Microscopically, a solitary fibrous tumor is characteristically a circumscribed neoplasm composed of variably cellular and patternless distributions of bland spindle and ovoid cells within variably collagenous stroma that frequently shows areas of dense hyalinisation, as well as interspersed large branching or “staghorn”- shaped thin-walled vessels. Immunohistochemical staining is very effective to distinguish solitary fibrous tumors from other fibroblastic tumors. Recently, NAB2–STAT6 gene fusion derived from inv12 (q13q13) has been reported as the genetic hallmark of solitary fibrous tumor. Complete local surgical excision appears to be the treatment of choice for solitary fibrous tumor of the head and neck region. Recurrence was reported in 5% of cases. The median recurrence-free interval was 36.5 months. We report the case of a solitary fibrous tumor of the temporal region, surgically excised and with no clinical and/or radiological signs of recurrence after 7 years of follow-up.
Highlights
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We present a rare case of head and neck solitary fibrous tumor.
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Surgical excision is the treatment of choice.
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We observed no recurrence after 7 years of follow-up.
1
Introduction
Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm of mesenchymal origin. It was first described by Klemperer and Rabin in 1931 [ ]. Before the widespread acceptance of the term “solitary fibrous tumor,” pleural SFT had been referred to by a number of other terms, including fibrous mesothelioma, benign mesothelioma, localized mesothelioma, subpleural fibroma, and localized fibrous tumor of the pleura, to distinguish it from the clinically more aggressive mesothelioma. Another synonymous term is hemangiopericytoma (HPC), described first in 1942 and originally thought to be a neoplasm arising from perivascular smooth muscle cells [ ]. For many years, HPC and SFT were considered as different entities. With the development of immunohistochemistry techniques and sophisticated cytogenetic analyses, it was shown that SFT have features and an immunohistochemical pattern that makes it almost indistinguishable from HPC. It has led to their unification as SFT in contemporary WHO classification. Initially, SFTs were thought to arise only in the pleural cavity, but other primary sites have been reported. In 1991, Witkin and Rosai reported the first recognized case within the head and neck region [ ]. Currently, it is estimated that 6–18% of all SFT arise within the head and neck region, representing approximately one quarter of all extrathoracic SFT [ ].
2
Case presentation
A 35-year-old man was referred to our Department in 2014 for the evaluation of a painless nodule in the left temporal region. On local examination, a relatively firm, well circumscribed, dome shaped mass with normal color was found in correspondence of the left temporal muscle.
Ultrasonography showed the presence of a solid, hypoechoic, oval nodule, with clear contours, 1,8cm in diameter, with moderate vascularization and located within a muscular structure. Arterial doppler analysis of the main vascular peduncle showed a regular systolic-diastolic modulation compatible with the presence of an anarchic vascularity ( Fig. 1 ) .
MRI revealed the presence of a solid nodular formation localized in the context of the superficial bundles of the left temporal muscle, with a homogeneous signal, not modifying in fat-sat acquisitions and without liquid component inside it. The margins of the nodule appeared well delimited and after the administration of the contrast medium there was a lively, rapid and complete enhancement ( Fig. 2 ).
Surgery was performed under general anesthesia. A pre-auricular skin incision was made extended to the left temporal region; a skin flap was prepared to highlight the site of neoformation. Then the incision of the temporal fascia and the removal of the rounded lesion that was included in the structure of the temporal muscle were performed ( Figs. 3–4 ).
