|Year : 2014 | Volume
| Issue : 3 | Page : 739-741
Primary synovial sarcoma of the maxilla
Manikkath Aparna1, Jayalakshmi Natarajan1, Chakravarty Arumugam2, Raghu Radhakrishnan1
1 Department of Oral Pathology and Microbiology, Manipal College of Dental Sciences, Manipal University, Manipal, Karnataka, India
2 Department of Operative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Manipal, Karnataka, India
|Date of Web Publication||14-Oct-2014|
Department of Oral Pathology and Microbiology, Manipal College of Dental Sciences, Manipal University, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
An innocuously appearing gingival mass in the maxilla revealed extensive osteolysis on radiographic examination. A rare clinical presentation of synovial sarcoma, appropriate diagnostic strategies and suitable treatment protocol in a 21-year-old male is reported herewith. It is only the third case of primary monophasic synovial sarcoma of the maxilla to be reported to the best of our knowledge and the first to have occurred in a male patient. The importance of considering synovial sarcoma in the differential diagnosis of any mass in the oral cavity is highlighted.
Keywords: Bcl2, CD99, epithelial membrane antigen, maxilla, primary synovial sarcoma, vimentin
|How to cite this article:|
Aparna M, Natarajan J, Arumugam C, Radhakrishnan R. Primary synovial sarcoma of the maxilla. J Can Res Ther 2014;10:739-41
| > Introduction|| |
Synovial sarcomas are aggressive malignancies comprising about 10% of soft-tissue sarcomas with incidence of 1.8-5 cases/million/year.  Although frequently found in relation to the extremities their intra-oral occurrence is extremely rare with only nine cases having been reported in the jaws excluding those arising in the temporomandibular joint. Oral synovial sarcomas are significant as they can be misdiagnosed owing to their rarity, well-defined appearance, slow growth and a multitude of histopathological features. This paper reports a case of primary synovial sarcoma of the maxilla highlighting the imaging findings, microscopic features, differential diagnosis and immunohistochemical work-up that lead to the final diagnosis.
| > Case report|| |
This was a case report of a 21-year-old male patient who presented with a painless outgrowth of the gingiva in the right maxillary alveolar region [Figure 1] that was noticed 2 months prior to consultation. The patient sought medical advice when the teeth in relation to the growth gradually became mobile. Intraoral examination divulged a firm, smooth, well-defined lobulated mass on gingiva, measuring about 3 × 2 cm extending from the distal aspect of lateral incisor to the distal aspect of first premolar. Canine and first premolar in relation to the growth was tested to be non-vital. The regional lymph nodes were not palpable. No significant loss of sensation of the infraorbital nerve or restriction of mouth opening could be detected.
Radiological examination revealed widening of the periodontal ligament space and discontinuity of lamina dura along the root of maxillary canine, along with poorly-defined radiolucency in relation to the apical aspects of canine and first premolar. Computed tomography scan showed a soft-tissue density and destruction of the right maxilla [Figure 2]. Incisional biopsy revealed a densely collagenous stroma with areas of vascularity and sparse inflammatory cells. Cells were predominantly spindly, arranged in short interlacing fascicles. Cells with vesicular nuclei, prominent nucleoli, occasional nuclear hyperchromatism and atypical mitotic figures were evident. The overlying stratified squamous epithelium was intact and the stroma adjacent to it was sparsely cellular [Figure 3]a and b. A panel of antibodies was employed to diagnose this entity whose initial impression was a spindle cell tumor.
|Figure 2: Computed tomography image reveals the extension of the soft tissue mass and destruction of bone|
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|Figure 3: (a) Photomicrograph showing a highly cellular submucosal stroma showing spindle shaped cells, which were arranged in short interlacing fascicles. The overlying epithelium is parakeratinised stratified squamous (H and E, ×4). (b) Photomicrograph showing cells of different sizes (H and E, ×20)|
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The neoplastic cells were focally positive for epithelial membrane antigen (EMA) [Figure 4]a, diffusely positive for vimentin [Figure 4]b, Bcl2 [Figure 4]c as well as CD99 [Figure 4]d. The tumor cells were negative for CD34 and S100. Complete metastatic evaluation of the patient ruled out the possibility of metastatic tumor. A diagnosis of primary monophasic synovial sarcoma of the right maxilla was made.
|Figure 4: (a) Photomicrograph showing the focal expression of epithelial membrane antigen in the tumor cells (×10). (b) Photomicrograph showing diffuse expression of vimentin in the tumor cells (×20). (c) Photomicrograph showing diffuse expression of Bcl2 in the cytoplasm of the spindle cells (×20). (d) Photomicrograph showing diffuse expression of CD99 in the cytoplasm and cell membranes of the tumor cells (×20)|
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The patient was treated by right partial maxillectomy followed by right supraomohyoid neck dissection. The resected tumor specimen confirmed the diagnosis. Adjuvant chemotherapy and radiotherapy have been advised. He has been under regular follow-up since 12 months and no recurrence has been reported to date.
| > Discussion|| |
Synovial sarcomas, designated so for their resemblance to the synovial tissue, are soft-tissue malignancies with significant morbidity and mortality. In rare instances, these tumors have been found to arise in sites away from the joints including the head and neck, lungs and the heart. Histogenesis of synovial sarcoma is poorly understood although its origin in undifferentiated cells of skeletal muscle lineage and myoblasts has been hypothesized.  Synovial sarcoma has thus been classified as a tumor of uncertain differentiation. 
Microscopically, these tumors are characterized by biphasic, monophasic and poorly differentiated varieties. The biphasic pattern comprises of spindle cell component and the epithelial glandular elements having diverse morphologic configurations. The monophasic forms are composed of spindled cells arranged as sheets or fascicles. The stroma in both types contain collagen, myxoid changes, cysts, calcifications, metaplastic bone, staghorn or hemangiopericytoma such as vasculature, scattered mast cells and mitosis. Poorly differentiated type comprises of primitive small round cells.  Immunohistochemistry shows tumor cells in synovial sarcomas to be positive for cytokeratin and/or EMA, vimentin, Bcl2, calretinin and CD99.
Several soft-tissue sarcomas present with a predominance of atypical spindle cells including tumors of fibroblastic, skeletal muscle, smooth muscle, neural, vascular and mixed differentiation, all of which were considered in the diagnostic work-up of the present case. Fibrosarcoma was excluded because of the lack of the typical herringbone pattern coupled with a focal presence of a hemangiopericytoma like vasculature and the demonstration of EMA in the neoplastic cells. The absence of tumor cells arranged in storiform pattern, histiocytes, foreign body or Touton giant cells and xanthoma cells eliminated a diagnosis of malignant fibrous histiocytoma. Despite the presence of epithelial markers, the possibility of a malignant peripheral nerve sheath was belied due to the absence of wavy nuclei, neuroid-type whorls and perivascular or subintimal involvement of blood vessels and negative staining of the tumor cells with S100. The diagnosis of rhabdomyosarcoma was eliminated due to the absence of spindle cells with cigar shaped nucleus, eosinophilic fibrillary cytoplasm exhibiting cross striations and storiform pattern and the demonstration of an epithelial phenotype by immunohistochemistry. Leiomyosarcoma was excluded due to the lack of cells arranged in well-defined fascicles at right angles to each other, absence of paranuclear vacuole, densely eosinophilic cytoplasm and positive immunoreactivity to EMA and Bcl2. 
Demonstration of reciprocal balanced translocation of the t (x; 18) (p11.2; q11.2) involving the SS18 and the SYT genes is the characteristic cytogenetic change detected in >95% of the cases of synovial sarcomas.  Multimodality therapy comprising extensive radical local excision, post-operative radiation therapy and chemotherapy is recommended. Tumor recurrences typically occur in the first 2 years. Metastasis is most commonly seen to the lungs, followed by lymph nodes and bone marrow. At 5-year survival rate varies from 25% to 50% respectively. 
In summary, we describe a case of primary monophasic synovial sarcoma of the maxilla. To the best of our knowledge, the maxilla has been the site of involvement in only two published cases [Table 1]. Therefore, the present report is the third to describe primary synovial sarcoma in the maxilla and the first of a male patient. This case attempts to highlights the significance of including synovial sarcoma in the working differential diagnosis of the malignant primary and metastatic spindle cell tumors of the oral cavity.
|Table 1: Clinico-pathologic features of the cases of primary synovial sarcomas of the jaws|
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]