Solitary fibrous tumors (SFTs) are rare tumors that are mostly found arising from the pleura. SFT of the parotid gland is a rare tumor; only a few cases have been described in the literature. SFTs are benign in most cases. Clinically, SFTs usually manifest as well circumscribed, slow-growing, smooth, and painless masses. CT-Scan and MRI are the most sensitive imaging procedures used. The treatment of choice is complete surgical excision of the lesion. Since recurrence and metastasis can take place after several years, a lifelong clinical and imaging regular follow-up is compulsory. In this paper, we describe the diagnostic and therapeutic challenges of the up-to-now biggest parotid SFT. The clinical presentation, surgical management, and pathological and immunohistochemistry findings are described.
Solitary fibrous tumor (SFT) was described by Klemperer and Rabin in 1931 as a tumor derived from the pleura [
Extrapleural SFTs have been reported in nearly all anatomic sites, with approximately 6% developing in the head and neck [
A 67-year-old female presented with a 10-year history of a progressively developing, tender mass in the left parotid region. Her medical history was unremarkable. Physical examination revealed a 16 × 18 cm firm, fixed, immobile, smoothly contoured mass without overlying erythema. There were no facial palsy, no tumor in the pharynx and larynx, and no palpable lymph nodes, and the oral mucosa was intact. On the postcontrast computed tomography scan (Figure
Postcontrast CT scan of the tumor.
CT angiography displaying the rich vascular network.
Histology revealed alternating hypocellular and high cellular areas demonstrating a population of densely packed, randomly arranged cells (Figure
(a) Areas with heightened cellularity. The cells range from round/ovoid to slightly spindle; they are arranged randomly or in short ill-defined fascicles. (b) At higher magnification the tumor cells have indistinct cytoplasm and oval nuclei, usually with inconspicuous nucleoli.
(a) A diffuse and strong cytoplasmic positivity of tumor cells is observed at this medium power magnification for CD34. (b) Vimentin immunohistochemical staining. (c) Strong cytoplasmic positivity for Bcl-2 is readily apparent.
SFT is extremely rare in the parotid [
According to the literature [
Diagnostic work up includes CT and/or magnetic resonance (MR) imaging, even if results may not be specific for SFT. On CT scan, SFT appears as a well-defined soft-tissue mass relatively hyperdense with respect to adjacent tissues, demonstrating heterogeneous enhancement after contrast administration. On MRI, SFT has a signal characteristic consistent with any soft tissue tumor, with intermediate signal intensity on T1-weighted images and enhancement on T2-weighted images [
Differential diagnosis is made with other enhancing lesions within the parotid gland, especially with pleomorphic adenomas and mucoepidermoid carcinomas. Large pleomorphic adenomas may have lobulated or poorly defined margins, while high grade mucoepidermoid carcinomas are scantily defined with heterogeneous internal architecture and may have associated cervical adenopathy [
Characteristically, SFT is a lobulated or nodular, firm, well-circumscribed, gray mass, surrounded by a pseudo-capsule, often with small satellite nodules separate from the main tumor [
Histological features associated with malignancy include high cellularity, pleomorphism, necrosis, high mitotic rate (>6 mitoses/10 hpf in tumors considered malignant), and/or infiltrative margins [
SFT shows immunoreactivity with vimentin and CD34, the major part of tumors displaying also positive results for bcl-2 and CD99. CD34 is the only consistently expressed and sensitive marker in SFT [
Immunohistochemistry and histology help in the differential diagnosis from other parotid tumors: pleomorphic adenoma, myoepithelioma, fibrous histiocytoma, spindle cell squamous cell carcinoma, schwannoma, neurofibroma, fibrosarcoma, myofibroblastoma, meningioma, melanoma, Kaposi sarcoma, and synovial sarcoma [
Traditionally, the treatment of SFT has been surgical resection with negative margins [
The authors declare that there is no conflict of interests regarding the publication of this paper.