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| Year : 2009 | Volume
: 52
| Issue : 4 | Page : 568-570 |
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| Monophasic synovial sarcoma of tongue |
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Atin P Agarwal, Tanuja M Shet, Rupali Joshi, Sangeeta B Desai, RF Chinoy
Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, India
Click here for correspondence address and email
| Date of Web Publication | 1-Oct-2009 |
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 Abstract | | |
Synovial sarcoma is a well defined morphologic entity extensively researched in literature. Synovial sarcoma displays a wide spectrum of clinical presentations and histologic appearances that may give rise to diagnostic dilemmas. One such unusual site in the head and neck area is the tongue. We report a case of monophasic synovial sarcoma of the tongue in a 22-year-old male. Microscopically, this tumor mimicked a poorly differentiated carcinoma which is more common at this site though the patient was young for this type of tumor. On immunohistochemistry, neoplastic cells were positive for cytokeratin, vimentin, calponin, CD99 and bcl2. Molecular studies - viz. reverse transcriptase polymerase chain reaction revealed a SYT-SSX translocation clinching the diagnosis. This paper highlights the immunohistochemistry profile and SYT-SSX translocation which helped arrive at an accurate diagnosis only because the index of suspicion for a monophasic synovial sarcoma is high. Keywords: Immunohistochemistry, molecular diagnosis, synovial sarcoma, tongue
How to cite this article:
Agarwal AP, Shet TM, Joshi R, Desai SB, Chinoy R F. Monophasic synovial sarcoma of tongue. Indian J Pathol Microbiol 2009;52:568-70 |
| Introduction | |  |
The World Health Organization (WHO) has defined synovial sarcomas (SS) as "mesenchymal spindle cell tumors which display variable epithelial differentiation, including glandular formation and have a specific chromosomal translocation t (x: 18) (p11; q11)".[1] Molecular studies for translocations in soft tissue tumors reveal that SS can present in varied sites with varied histologic patterns.
The overall incidence of SS at all sites ranges from 5.6 to 10%. Involvement of the head and neck region is rare.[2],[3] So far, fewer than 100 cases have been reported in literature and they occur in the soft palate, tongue, larynx, hypo pharynx and cervical esophagus.[4]
We describe the clinical, morphologic, immunohistochemical and molecular features of a case of monophasic SS in a young man with emphasis on differential diagnosis and clinical outcome. It is important to recognize this entity in the head and neck region because the main stay of treatment is wide excision of the primary tumor and not chemotherapy or regional node dissection.
| Case Report | | |
A 22-year-old man presented with a recurrent 5x3x2 cm growth at the base of the tongue. The lesion had produced a bulge on the surface and had partly ulcerated the mucosa due to which the patient faced difficulty in eating and speaking. There were no definitive results of his first biopsy conducted about three to four years ago.
On general examination, the patient was in fair general condition with no hepatosplenomegaly or lymphadenopathy and had a normal hematological and biochemistry profile. A wide excision with clear margins was done elsewhere and reported as an undifferentiated carcinoma. The specimen, along with two stained slides and a single paraffin block, was referred at our institute for a second opinion. Five micron thick sections were cut from the paraffin embedded block for routine hematoxylin and eosin (H and E). For immunohistochemistry (IHC), five micron thick sections were cut and mounted on poly-L-lysine coated slides. Primary antibodies included epithelial membrane antigen (EMA monoclonal 1:100 DAKO), cytokeratin (CK monoclonal 1:100 DAKO), CD99 (monoclonal 1:50 DAKO, vimentin (monoclonal 1:50 DAKO), S100 (polyclonal 1:300 DAKO), HMB45 (monoclonal 1:50 DAKO), bcl2 (monoclonal 1:50 DAKO) and calponin (monoclonal 1:50 DAKO). IHC staining was done using the Avidin-Biotin complex (ABC) method, diaminobenzidine serving as a chromogen. Counterstaining was performed by the hematoxylin stain. Tumor tissue was subjected to reverse transcriptase polymerase chain reaction (RT-PCR) studies on the paraffin block
On gross examination, the lesion was polypoidal measuring 5x3x2cm. Histology revealed a polypoid, high grade tumor infiltrating the muscle. The overlying epithelium was thinned out and partially ulcerated but devoid of an in- situ area or dysplasia [Figure 1]. The tumor was cellular, mitotically active and composed of non-collagen forming closely packed spindly cells. Occasional cell had nucleoli [Figure 2]. Differentiating features like frank epithelioid areas, areas of neural differentiation or rosettes were not seen.
On IHC, the tumor cells were strongly positive for CD99 (Mic2), calponin and focally for CK, vimentin and bcl2. Tumor cells were negative for EMA, S100 protein and HMB45.
RT-PCR was reported positive for SYT-SSX translocation [Figure 3]. As primitive neuro ectodermal tumor (PNET) was one of our differential diagnoses, RT-PCR for EWS-FLI1 translocation was also done; it was negative. Patient was advised to take radiotherapy but did not follow up subsequently.
| Discussion | | |
SS is a rare and unique tumor which in reality is a form of carcinosarcoma. Many misconceptions persist regarding its true histogenesis. Immunohistochemistry, electron microscopy and more recently molecular pathology have helped us understand that they originate from undifferentiated or pleuripotent stem cells. Today, SS has been recorded almost everywhere in the body.
SS form 5.6 to 10% cases of all soft tissue tumors.[2],[3] However, the incidence at our institute, a teaching cancer referral centre, is 14% of all soft tissue tumors.[5] Synovial sarcomas are most commonly seen in adolescents and young adults between 15-40 years of age.[2] The patient under study was 22 years of age.
The most common site involved by SS is the lower limb (60-75%), followed by the upper limb (15-20%).[2] The head and neck region accounts for six to seven per cent of all the cases of SS.[2] Fortuno-Mar et al.[6] reviewed literature and found 80 cases of head and neck SS, out of which seven were of lingual origin. The single most common site of head and neck SS was the hypopharynx.[5]
Microscopically, SS cases with a biphasic pattern are easy to recognize when located in any area of the body. However, at rare sites like the head and neck, they may sometimes be misdiagnosed as epithelial tumors such as poorly differentiated squamous carcinomas or myoepitheliomas.[5] Monophasic SS is even more likely to be misdiagnosed and have been mistaken for other soft tissue tumors like hemangiopericytoma, fibrosarcoma and malignant peripheral nerve sheath tumor (MPNST).[5]
In our patient, the tumor lacked the thick vessels with verrocay bodies and intersecting collagen bundles and geographic areas of necrosis usually seen in MPNST. Rosetteoid pattern suggestive of PNET was also not appreciated. Lack of melanin pigment, prominent eosinophilic nucleoli and negative IHC (HMB45) ruled out a diagnosis of melanoma. Epithelial differentiation was not evident to label it a sarcomatoid carcinoma. Our initial differential diagnosis included a PNET, a poorly differentiated carcinoma, and a monophasic synovial sarcoma.
Most SS cases are immunoreactive to CK and EMA and hence may be mistaken for carcinomas. Around 60-70% of synovial sarcomas are positive to CD99 (Mic2) and 30% to S100 protein. In addition, bcl2 and calponin show a strong and diffuse reactivity in 75-100% cases of synovial sarcomas.
In the present study, the tumor cells were positive for Mic2, calponin and focally for CK, vimentin and bcl2. They were negative for EMA, S100 protein and HMB45. The immunohistochemical profile of a synovial sarcoma overlapped with that of a PNET.[7] Hence, for confirmation of the diagnosis of monophasic and poorly differentiated synovial sarcoma, electron microscopy and molecular studies were advised. Electron microscopy (EM) indicates that synovial sarcomas originate from undifferentiated or pleuripotent stem cells.[8] However, in the present case, EM was not performed.
Presently, detection of the t(X:18)(SYT;SSX) translocation in a spindle to round cell sarcoma using RT-PCR or in situ Hybridization (ISH) is virtually synonymous with a diagnosis of SS.[9] In our case, this translocation was demonstrated. The SYT-SSX translocation also influences the morphologic appearance in synovial sarcoma. Biphasic SS is more often positive for SYT-SSX1 translocation, while monophasic SS is positive for SYT-SSX2 translocation.[10]
The ideal treatment for head and neck SS is surgery with complete excision of the tumor.[8],[11],[12] If it is not possible to excise the tumor, then the role of post operative radiotherapy is recommended. Accurate diagnosis of SS helps rule out a sarcomatoid carcinoma and thus avoids unnecessary nodal dissection. It is important to differentiate SS from PNET as in the latter, chemotherapy is required. SS should also be distinguished from MPNST as a different chemotherapy protocol may be used.
| Conclusion | | |
In summary, SS cases are known to occur in the head and neck region. A low index of suspicion for monophasic or poorly differentiated synovial sarcomas may lead to an erroneous diagnosis of carcinoma or sarcoma of different histogenetic type or PNET. Since treatment decisions are based on histopathology, the judicious use of IHC, EM and molecular studies would help resolve the diagnostic dilemma.
| References | | |
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| 2. | Spillane AJ, A'Hern R, Judson IR, Fisher C, Thomas JM. Synovial sarcoma: A clinicopathologic, staging, and prognostic assessment. J Clin Oncol 2000;18:3794-803. |
| 3. | Singer S, Baldini EH, Demetri GD, Fletcher JA, Corson JM. Synovial sarcoma: Prognostic significance of tumor, size, margin of resection, and mitotic activity for survival. J Clin Oncol 1996;14:1201-8. |
| 4. | Bertolini F, Bianchi B, Pizzigallo A, Tullio A, Sesenna E. Synovial cell sarcoma of the neck: Case report and review of the literature. Acta Otol rhinol laryngol Ital 2003;23:391-5. |
| 5. | Pai S, Chinoy RF, Pradhan SA, D'Cruz AK, Kane SV, Yadav JN. Head and neck synovial sarcomas. J Surg Oncol 1993;54:82-6. |
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| 8. | Roth JA, Enzinger FM, Tannenbaum M. Synovial sarcoma of the neck: A follow-up study of 24 cases Cancer 1975;35:1243-53. |
| 9. | Tsuji S, Hisaoka M, Morimitsu Y, Hashimoto H, Shimajiri S, Komiya S, et al. Detection of SYT-SSX fusion transcripts in synovial sarcoma by reverse transcription-polymerase chain reaction using archival paraffin-embedded tissues. Am J Pathol 1998;153:1807-12. |
| 10. | Antonescu CR, Kawai A, Leung DH, Lonardo F, Woodruff JM, Healey JH, et al. Strong association of SYT-SSX fusion type and morphologic epithelial differentiation in synovial sarcoma. Diagn Mol Pathol 2000;9:1-8. |
| 11. | Bukachevsky RP, Pincus RL, Shechtman FG, Sarti E, Chodosh P. Synovial sarcoma of the head and neck. Head Neck 1992;14:44-8. |
| 12. | Shmookler BM, Enzinger FM, Brannon RB. Orofacial synovial sarcoma. Cancer 1992;50:269-76. |
Correspondence Address:
R F Chinoy
Annexe Building, 8th Floor, Dr. Ernest Borges Road, Parel, Mumbai-400 012
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0377-4929.56167
[Figure 1], [Figure 2], [Figure 3] |
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