Solitary Fibrous Tumour of the Parotid Gland: A Case Report and Review of the Literature

Head and Neck Solitary Fibrous Tumor Presenting as Salivary Gland Tumor: Two Case Reports and Review of the Literature

Solitary fibrous tumors (SFTs) are soft tumors (mesenchymal origin) that most likely develop from adult mesenchymal stem cells. SFTs are not common in the head and neck region, and the characteristics of tumors in this location are unclear. The present study describes the clinicopathological findings of 2 cases of SFTs arising in the parotid gland and buccal space, presenting as salivary gland tumors. The first case is a 76-year-old man presenting with a painless tumor on the right parotid gland who subsequently underwent partial superficial parotidectomy. According to the results of histopathological analysis, the tumor consisted of stellate and spindle-shaped cells proliferating on a mucous-like substrate. Immunohistochemical staining revealed that neoplastic cells were positive for CD34, vimentin, Bcl2, and STAT6. The second case is of a 64-year-old man presenting with a painless lump on his right cheek. Based on the findings of fine needle aspiration cytology, a tumor derived from myoepithelial cells of the minor salivary gland or a nonepithelial tumor was suspected. The patient underwent surgical resection via an intraoral approach. Histopathologically, the tumor consisted of spindle-shaped cells with rod-shaped or irregular nuclei. Immunohistochemical staining revealed that the neoplastic cells were positive for CD34, CD99, Bcl2, and STAT6. Briefly, SFT should be considered in the differential diagnosis of a well-marginalized lesion in the salivary gland and oral cavity. STAT6 immunohistochemistry is the most specific and sensitive method of diagnosing SFT. A thorough understanding of the morphological changes associated with SFT and their correlation with clinical, immunohistochemical, and molecular characteristics is important to avoid misdiagnosis.

Solitary fibrous tumour of the parotid gland: a case report and a 15-year literature review

Solitary fibrous tumour (SFT) is uncommonly found in the salivary glands and is a rare group of spindle-cell tumours. A review of literature revealed only 40 reported cases of SFT of major salivary glands over a 15-year period from 2004 to 2018. SFTs of the salivary glands are usually benign, although rarely, can be aggressive and may sometimes recur after initial resection. Histology and Immunohistochemistry are the most important criteria to distinguish SFT from other head and neck tumours. SFTs strongly stain for CD34 and hence is the most frequently used stain for diagnosis. All reported SFT cases with available information on immunohistochemical stains were positive for CD34. Recently, immunohistochemistry for STAT6 has been introduced as a surrogate diagnostic marker for SFT that is highly sensitive and specific. We report a case of a 51-year-old Chinese gentleman who presents with a 3-month history of a left parotid tumour that required a subtotal parotidectomy for complete excision. It was diagnosed as SFT based on histology and immunohistochemical features. He was followed-up for 3 months post-operatively with no clinical evidence of recurrence. This case proposes that, although rare, SFT should be considered in the differential diagnosis of soft-tissue tumors in the major salivary glands. An awareness of this rare entity will help clinicians and pathologists better manage similar patients in the future.

A New Primary in Parotid Gland with History of Treated Mediastinal Solitary Fibrous Tumour

Solitary fibrous tumours (SFTs) are rare tumours in the head and neck region. They have been reported in many anatomic sites but occurrence in the parotid gland is exceptional. We report a very rare finding of a benign SFT of the parotid gland in a patient with a past history of excision of a malignant type of mediastinal tumour. It is important that clinicians are aware of the possible existence of SFT in the parotid as a synchronous lesion or occurrence of the same disease later on elsewhere when SFT is diagnosed at one anatomical site. This case report illustrates that regular clinical and imaging follow-up is essential in SFTs to look for the appearance of new lesions in the other anatomic site.

Solitary fibrous tumor occurring in the parotid gland: a case report

Background

Solitary fibrous tumor is an uncommon spindle cell neoplasm of unknown origin. It has been reported in many anatomic sites, with a rare occurrence in the head and neck region. Solitary fibrous tumors of the parotid gland are exceptional; their clinical and radiologic features are non specific, often mimicking more common salivary gland tumors. Pathologic examination and immunohistochemistry are required to make the correct diagnosis. The prognosis is favorable, with most tumors being benign, and complete surgical resection is the treatment of choice.

Case presentation

We report the case of a 42-year-old man who presented with a painless mass involving the parotid gland. A parotidectomy was performed, and follow up was unremarkable. Gross examination showed a well circumscribed, firm tumor measuring 3,4 cm. Histologically, the tumor was composed of a spindle cell proliferation of variable cellularity, with staghorn vessels. A panel of immunohistochemical stains was performed, and confirmed the diagnosis of parotid gland solitary fibrous tumor.

Conclusion

In this report we aim to increase awareness of this rare entity among clinicians and pathologists, and to emphasize the role of immunohistochemistry in confirming the diagnosis.