Synovial sarcoma of the pyriform sinus: An extremely rare case and literature review

Emre Polat; Huseyin Toprak; Yagmur Basak Polat; Sahande Elagoz; Fadlullah Aksoy; Orhan Ozturan

doi:10.4103/sjoh.sjoh_54_22

CASE REPORT

Year : 2023 | Volume : 25 | Issue : 1 | Page : 38-41

Synovial sarcoma of the pyriform sinus: An extremely rare case and literature review

Emre Polat¹, Huseyin Toprak², Yagmur Basak Polat², Sahande Elagoz³, Fadlullah Aksoy¹, Orhan Ozturan¹
¹ Department of Otorhinolaryngology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
² Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
³ Department of Pathology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey

Date of Submission	20-Oct-2022
Date of Decision	25-Nov-2022
Date of Acceptance	26-Nov-2022
Date of Web Publication	20-Mar-2023

Correspondence Address:
Dr. Emre Polat
Department of Otorhinolaryngology, Faculty of Medicine, Bezmialem Vakif University, 34093- Istanbul
Turkey

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sjoh.sjoh_54_22

Abstract

Synovial sarcoma (SS) is a malignant mesenchymal tumor usually seen in young adults. Most cases occur in the extremities, especially the lower extremities. It is rarely seen in the head-and-neck region, and localization in the larynx and hypopharynx is even rarer. Approximately 20 immunohistochemically defined cases of laryngeal and hypopharyngeal SSs have been reported so far in the literature. We outline the case of a patient with primary hypopharyngeal SS who presented with hoarseness.

Keywords: Head and neck, pyriform sinus, synovial sarcoma

How to cite this article:
Polat E, Toprak H, Polat YB, Elagoz S, Aksoy F, Ozturan O. Synovial sarcoma of the pyriform sinus: An extremely rare case and literature review. Saudi J Otorhinolaryngol Head Neck Surg 2023;25:38-41

How to cite this URL:
Polat E, Toprak H, Polat YB, Elagoz S, Aksoy F, Ozturan O. Synovial sarcoma of the pyriform sinus: An extremely rare case and literature review. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2023 [cited 2023 Jun 4];25:38-41. Available from: https://www.sjohns.org/text.asp?2023/25/1/38/372140

Introduction

Synovial sarcoma (SS) is a malignant mesenchymal tumor. It constitutes 5%–10% of all soft tissue sarcomas.^[1] SS is most commonly seen in individuals between 15 and 40 years old, and 90% of cases occur in individuals under the age of 60 years.^[1] Tumors in the lower extremities account for approximately 70% of cases.^[2] SS seldom appears in the head-and-neck region, with only 3% of SSs appearing in the head and neck.^[2] Among head-and-neck SSs, laryngeal and hypopharyngeal SSs are even rarer, with about 20 immunohistochemically defined cases having been reported to date.^[3] We present a patient with a hypopharyngeal SS, on whom the authors operated.

Case Report

A 54-year-old male patient was admitted to our university hospital with complaints of hoarseness and difficulty breathing for the previous 1 month. He was not a smoker. Flexible laryngoscopic examination revealed a benign cystic lesion in the hypopharynx region, spreading from the right pyriform sinus to the vocal cord and covering it. Routine blood tests revealed no abnormalities. Contrast-enhanced neck computed tomography (CT) showed right pyriform sinus localization and a round, well-circumscribed, hyperdense lesion sized 3 cm × 2 cm × 2 cm with segmental calcification on the periphery extending to the vocal cord [Figure 1].

Figure 1: CT scan with contrast of the neck. (a) Sagittal view. (b) Coronal view. (c) Axial view in the right pyriform sinus localization, a round-shaped, well-circumscribed hyperdense lesion and segmental calcification on the periphery extending to the vocal cord were detected (white arrow). CT: Computed tomography

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Based on the radiological and clinical findings, we thought that the lesion was a benign tumor and decided to make an excision to confirm the diagnosis. The patient was taken into the operating theater for a biopsy. Well-circumscribed tumoral tissue with a diameter of about 3 cm was seen in the right pyriform sinus. Tumoral excision was performed under general anesthesia with a transoral endoscopic-assisted approach. This tissue was completely excised by pericapsular dissection.

The histopathological analysis revealed a 3 cm × 2 cm, partly encapsulated, hard elastic, gray-white, nodule-like tissue segment. This was a malignant mesenchymal tumor with peripheral calcification and ossification in the submucosal area, expansive margins, and epithelioid morphology, including short bundles of spindle cells in focal areas. No necrosis was observed. Mitosis 3–4/10 HPF. Atypical mitosis was not seen. The differentiation score was 3. The tumor was histological grade 2 (FNCLCC scoring system), with no lymphovascular invasion. No tumor was observed in the surgical margins. Immunohistochemistry revealed the following: pancytokeratin as single cells+, cytokeratin 7 focal+, Epithelial membrane antigen (EMA) focal+, CD99 membranous+, CD 56+, Ki-67 5%–7%, and TLE1+. These findings were consistent with biphasic SS [Figure 2].

Figure 2: (a) Spindle cells forming short bundles and epithelioid tumor cells with oval round nuclei forming a solid group and trabeculae structures (H and E, ×100). (b) Tumor cells with epithelioid appearance forming trabeculae structures within prominent hyalinization areas (H and E, ×100). (c) Patchy positive with CK7 staining (×100), (d) Diffuse nuclear positive staining with TLE1 (×200)

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A follow-up examination was performed 1 month after surgery, including positron emission tomography-CT, neck magnetic resonance imaging, and neck CT [Figure 3]. No findings suggestive of recurrence or residue were found in the imaging.

Figure 3: Postoperative CT scan, with contrast, of the neck. (a) Sagittal vie. (b) Coronal view. (c) Axial view. No finding suggestive of recurrence or residue was found in the imaging. CT: Computed tomography

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Our patient was invited to a multidisciplinary meeting consisting of otolaryngology, medical oncology, radiation oncology, and radiology consultants to be evaluated for advanced treatment. At this meeting, it was determined that adjuvant chemotherapy treatment was not necessary, and it was decided that the patient should receive radiotherapy. The patient, who came from another country, decided to receive radiation therapy in his own country. We did not conduct any further follow-up after this meeting.

Discussion

The term “synovial sarcoma” was first used as a misnomer in the nineteenth century because of the histological resemblance of the tumor to the joint synovium.^[4] Later, this tumor was shown to originate from pluripotent mesenchymal stem cells.

SS accounts for 5%–10% of all soft tissue sarcomas. It predominantly occurs in young adults, with 90% occurring in individuals younger than 60 years old. The majority (80%–95%) of SS tumors occur in the extremities, and two-thirds have been reported in the lower extremities, although SS has been documented in almost every anatomical region. Although they are rare, accounting for fewer than 5% of all SSs, head-and-neck SSs are the second most common SS tumors. Those originating in the larynx and hypopharynx are even rarer.^{[1],[2],[3],[5]} According to previous studies, the most common location of SS in the head and neck is the upper aerodigestive tract (the oral cavity, oropharynx, hypopharynx, and larynx).^{[2],[6],[7],[8],[9]} In our patient, the tumor was located in the hypopharyngeal area. It was localized in the pyriform sinus, extending to the vocal cord.

The first case report of SS in the pharynx region was published by Jernstrom in 1954.^[10] Later, cases of laryngeal SS were published by Gatti and Miller in 1975.^[11],[12] Since these reports were published, several additional cases of SS of the larynx and hypopharynx have been published as case reports, for a total of approximately 20 reported cases of immunohistochemically defined laryngeal and hypopharyngeal SS to date.^[3]

SS generally grows slowly and can appear benign in imaging studies. The size of the tumor varies, usually appearing as an asymptomatic mass until it reaches sufficient volume to exert pressure on adjacent structures. For these reasons, SS is the most frequently misdiagnosed soft tissue malignancy.^{[1],[2],[13],[14]}

The most common clinical symptoms of SS of the head and neck are dysphagia, odynophagia, hoarseness, and a painless mass that can bleed.^[6] Although the benign appearance and slow growth are characteristic, the prognosis is poor. SS tends to recur locally and frequently exhibits hematogenous distant metastases, especially to the lung, lymph nodes, and bone. Lymph node involvement is present in 15%–20% of patients; however, this does not affect survival. The average 5-year survival in head-and-neck SSs has been shown to be 40%–70%, while the recurrence rate is 40%. Patients with paraspinal or skull base tumors are significantly more likely to relapse than those with tumors of the aerodigestive tract.^{[6],[7],[15],[16]}

Wushou et al.^[2] evaluated clinicopathological differences such as age, gender, tumor location (superficial, medium, and deep), tumor size, tumor extension, surgical margins, neck dissection, histological type, and treatment type in head-and-neck SS. In their study, tumor size was shown as the only independent adverse prognostic factor to determine the overall survival. Patients with tumors >5 cm in diameter had a higher risk of local tumor recurrence, distant metastasis, and mortality than patients with a tumor diameter ≤5 cm. In addition, Gopalarakishnan et al.^[6] observed that the time between diagnosis and recurrence was lower in patients with tumor sizes larger than 5 cm.

Previous studies have indicated that high mitotic index, high grade, metastatic or recurrent disease, and initial tumor size are associated with lower survival.^[6] In our patient, the diameter of the tumor was approximately 3 cm.

Imaging methods are insufficient to make an initial diagnosis. A definitive diagnosis is made based on tumor morphology, immunohistochemistry, and molecular studies.^[3]

Radiologically, the SS tends to be large and lobulated. Calcification is seen radiologically in 30% of cases. No correlation was found between imaging findings and pathological subtypes.^[1] The appearance of a well-circumscribed, painless mass on tumor imaging, together with a fibrous pseudocapsule contributes to its benign appearance.^[17]

On computed tomography, it is usually mildly hypodense and well-circumscribed. Calcification is detected at a rate of 30%–50%. Lymph node involvement is observed in 15%–20% of head-and-neck SS cases. CT rarely detects this lymph node involvement.^[16],[18]

When we looked at the contrast-enhanced neck CT taken preoperatively in our patient, it was a well-circumscribed, benign mass, similar to the literature. There was no cervical lymph node involvement finding on the CT scan.

Some head-and-neck tumors may have imaging features similar to those seen in SS.^[13] Lymphoma, Ewing's sarcoma, fibrosarcoma, schwannomas, neurofibromas, ectopic tumors of salivary glands, hemangiopericytoma, and malignant peripheral nerve sheath tumor should be considered in the differential diagnosis.^[9],[18]

Over 90% of SS cases show t (x; 18) translocation with the fusion between the SSX1 or SSX2 and SYT genes. FISH and reverse transcription polymerase chain reaction were used for rapid diagnosis of SS. It is an invaluable method to confirm the diagnosis.^[1],[13]

No established treatment algorithm is determined by controlled studies in head-and-neck SS. The current treatment is complete excision with wide margins. The use of radiotherapy is for local control after resection. The role of chemotherapy in combination is also controversial.^[16]

Harb et al.^[7] recommended neoadjuvant chemotherapy for tumors with a risky initial site (e.g., the skull base or paraspinal neck) and >5 cm. According to them, postoperative chemotherapy can reduce the risk of local recurrence.

Conclusion

Hypopharyngeal SSs are extremely rare malignant tumors. The treatment approach should include a multidisciplinary team of physicians consisting of specialists in head-and-neck surgery, radiology, radiation oncology, and medical oncology. Its slow growth and radiological appearance of a benign tumor at first glance are very important and misleading points. Treatment should be initiated without delay.

Acknowledgements

A consent form was obtained from the patient to publish the case as a scientific article.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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