Synovial sarcoma

Abstract

Synovial sarcoma is not common in the head and neck region. Because its histopathologic features are many and varied, it is often misdiagnosed. We report a case of biphasic synovial sarcoma of the posterior pharyngeal wall, and we discuss the clinical and pathologic features of this case.

Introduction

Synovial sarcoma is a rare malignant tumor that derives from a mesenchymal precursor stem cell that is unrelated to mature synovial tissue. Its behavior in the head and neck region is similar to that of a synovial sarcoma that involves the extremities, where the tumor is most common. We report a case of a biphasic synovial sarcoma of the posterior pharyngeal wall.

Case report

A 54-year-old man was referred to the ENT Department by the Department of Gastroenterology. He had complained of progressively worsening dysphagia and symptoms of acid reflux. He reported no other symptoms relating to the ear, nose, and throat, and he had no history of a loss of weight or appetite. He had given up smoking 30 years earlier.

Examination revealed the presence of a pedunculated mucosal lesion on the posterior pharyngeal wall; the mass was situated to the left of the midline and just above the piriform fossa. No cervical lymphadenopathy was palpable. Findings on the remainder of the ENT examination were normal. A lateral neck x-ray demonstrated an abnormal protrusion of soft tissue from the posterior pharyngeal wall at the level of C3 (figure 1).

[FIGURE 1 OMITTED]

The patient underwent a pharyngoscopy, and the mass was removed as an excisional biopsy under general anesthesia. Histologic examination revealed that the tumor was made up of fibroblast-like spindle cells, among which epithelium-like cells were arranged in variable patterns of solid nests, interconnected cords, glandular formations, and cleft-like spaces (figure 2). Most of the spindle cells and a lesser proportion of the epithelial cells were reactive for the mesenchymal marker vimentin (figure 3). The epithelial markers cytokeratin, CAM 5.2, and epithelial membrane antigen (EMA) highlighted the delicate structures of the epithelial component (figure 4). The excision of the lesion was deemed incomplete.

[FIGURES 2-4 OMITTED]

The patient subsequently underwent a partial pharyngectomy with radial forearm flap reconstruction and preservation of the larynx. He made a complete recovery and was discharged home I week postoperatively. He was followed monthly at our multidisciplinary head and neck clinic, and at 12 months, he remained free of recurrence.

Discussion

Synovial sarcoma is an aggressive tumor that originates in the mesenchymal tissue. Despite its name, it rarely arises from mature synovial tissue. Tumors of the head and neck account for 3 to 10% of all synovial sarcomas. (1) Jernstrom published the first reported case ofa synovial sarcoma of the head and neck (hypopharynx) in 1954. (2) Since then, synovial sarcomas have been reported at other sites in the head and neck, including the nasopharynx, retropharynx, hypopharynx, laryngopharynx, parapharyngeal space, and esophagus. (3-12) Synovial sarcoma classically affects patients between the ages of 15 and 40 years, (10) and the proportion of male-to-female patients is 3:2. (9)

Our patient presented with nonspecific swallowing symptoms, which highlights the importance of a complete clinical evaluation of any patient who presents with such vague symptoms. No appreciable difference has been reported in the biologic activity of a synovial sarcoma in the head and neck and a synovial sarcoma at any other site, (1) but reports on survival data are conflicting. Pai et al reported that survival in cases of neck disease was higher than that in cases of limb tumors. (13) On the other hand, Kartha and Bumpous found that the 5-year survival rate for patients with head and neck synovial sarcoma was 40%, which is substantially lower than the 60% 5-year survival rate reported in the literature for synovial sarcoma at all other sites. (14)

Histologically, three variants of synovial sarcoma have been described: biphasic, monophasic fibrous, and monophasic epithelial. The classic features include spindle cells and interposed epithelial elements with a delicate cleft-like glandular pattern highlighted by cytokeratin immunohistochemistry. The spindle cell component strongly expresses vimentin, while the epithelial element is positive for cytokeratin, CAM 5.2, and EMA, which are hallmarks of biphasic synovial sarcoma.

Preoperatively, computed tomography and magnetic resonance imaging are the investigations of choice to determine the location and extent of the tumor.

Primary surgical excision is the mainstay of treatment; radiotherapy is reserved for residual or recurrent disease. (15) Postoperative radiotherapy is said to decrease the likelihood of local recurrence, but it has not improved long-term survival. (11) The role of chemotherapy is controversial, (16) although Lenoir et a1 (12) reported a dramatic regression in tumor size in a 15-month-old patient with a retropharyngeal synovial sarcoma after treatment with a combination of ifosfamide, vincristine, and actinomycin D. The future role of both radiotherapy and chemotherapy in the management of synovial sarcoma needs to be determined by a prospective study.

Favorable prognostic indicators include an early diagnosis, small tumor size (<5 cm), younger age (<20 yr), and a wide surgical excision. (15,17,18) Of these, tumor size is the single most important prognostic determinant, as tumors of 10 cm in diameter or larger are associated with a poor prognosis. (16)

Amble et al reported a series of 14 patients who had been treated for synovial sarcoma of the head and neck over a 30-year period, and they found that recurrent or metastatic tumors arose between 4 and 62 months after the development of the original tumor. (15) Their findings emphasize the need for long-term follow-up. Wright et al found that metastases tend to be bloodborne in most cases, with l0 to 20% of patients experiencing lymph node metastasis. (19) According to Nadig et al, lung metastasis accounts for more than 90% of all metastases. (3)

Because head and neck synovial sarcoma in clinical practice is so uncommon, early diagnosis is difficult and the treatment protocol is unclear. Therefore, every case report should include complete information on presentation and management. Also, long-term prognostic indices need to be evaluated.

References

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(18.) Thompson RC, Jr., Garg A, Goswitz J, et al. Synovial sarcoma. Large size predicts poor outcome. Clin Orthop 2000;(373):18-24.

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From the ENT Department (Dr. Agada, Dr. Murphy, Dr. Sharma, and Dr. Stafford) and the Department of Pathology (Dr. Karsai), Hull Royal Infirmary, Hull, U.K.

Reprint requests: Mr. Frank Agada, 10 Pavilion Way, Newton Hill, Wakefield WF1 3AJ, UK. Phone: 44-19-2437-4054; fax: 44-11-3392-3165; e-mail: foagada@aol.com

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