Journal of Cancer Research and Therapeutics

: 2018  |  Volume : 14  |  Issue : 8  |  Page : 267--269

Primary renal synovial sarcoma: A case report and literature review

Yong Huang1, Dawei Liu2, Junhang Luo3, Wei Chen3,  
1 Department of Urology; Department of Emergency, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China
2 Department of Pathology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China
3 Department of Urology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China

Correspondence Address:
Wei Chen
Department of Urology, The First Affiliated Hospital, Sun Yat-sen University, No. 58, Zhongshan 2nd Road Guangzhou 510080


Synovial sarcomas (SSs) are very rare, poorly studied tumors that generally occurs around joint and muscle tendons. Primary SSs of the kidney are even rarer, accounting for <2% of all malignant renal tumors. We report the case of a 44-year-old man who was diagnosed with primary renal SS on the basis of imaging, histopathological, and immunohistochemical examination. We also present a comprehensive review of the literature, with a focus on the differential diagnosis and treatment of renal tumors.

How to cite this article:
Huang Y, Liu D, Luo J, Chen W. Primary renal synovial sarcoma: A case report and literature review.J Can Res Ther 2018;14:267-269

How to cite this URL:
Huang Y, Liu D, Luo J, Chen W. Primary renal synovial sarcoma: A case report and literature review. J Can Res Ther [serial online] 2018 [cited 2022 Jan 19 ];14:267-269
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Synovial sarcomas (SSs) account for 5–10% adult soft tissue sarcomas and occur mostly in the proximity of large joints.[1] SSs have been reported in the thoracic and abdominal walls, head and neck region, retroperitoneum, bone, lung, and prostate.[1],[2] Renal SSs, first described by Faria et al. in 1999, are very rare.[3] Further, since they are indistinguishable from the more common renal cell carcinoma, they can be diagnosed only after sarcomatoid renal cell carcinoma, sarcomatoid transitional cell carcinoma of the renal pelvis, and angiomyolipoma have been excluded.[4] We describe a case of primary renal SS and review the latest related literature.

 Case Report

During an annual routine physical examination in August 2015, a 44-year-old man was found to have an asymptomatic lesion in the right kidney. His medical history was unremarkable. Computed tomography (CT) showed a large heterogeneous mass in the upper pole of the right kidney. It measured 9.7 cm in its greatest dimension and showed a subcapsular hematoma [Figure 1]. Hemogram and blood biochemistry results were within normal limits. Renal cell carcinoma with no evidence of lymphadenopathy or metastatic disease was diagnosed preoperatively. The patient underwent a right radical nephrectomy without complications.{Figure 1}

On macroscopic examination, the resected tumor was spherical, measured 8 cm × 7 cm × 10 cm, and infiltrated the upper part of the renal pelvis. Its cut surface was yellow-brown in color. Histological examination of the cross-section showed that the tumor comprised spindle cells arranged in solid, woven, or intersecting fascicles with focal necrosis. The cells showed scanty cytoplasm and obvious mitotic figures [Figure 2]. Immunohistochemical staining yielded positive results for epithelial membrane antigen (EMA), actin, and Ki67 and indicated diffuse expression of Bcl-2 [Figure 3]. S-100, CD34/CD117, desmin, and CK7/CK8/18 were not expressed. Using fluorescence in situ hybridization, the number of conspicuous red-green split signals was counted from at least one hundred cancer cells, and SYT gene breaking was considered positive since the signal count exceeded 15% [Figure 3]. The final diagnosis was poorly differentiated primary monophasic SS of the kidney. The patient refused systemic chemotherapy and cellular immunotherapy and had an uneventful recovery during 3 months of follow-up.{Figure 2}{Figure 3}


Primary renal sarcoma is a rare neoplasm, and leiomyosarcoma is the most common type, followed by rhabdomyosarcoma, chondrosarcoma, liposarcoma, angiosarcoma, hemangiopericytoma, and osteosarcoma.[1] Primary renal SS is even rarer, with fewer than fifty cases reported thus far. Our recent literature search showed that only clinical and imaging characteristics are not sufficient to definitively diagnose primary renal SS and the signs and symptoms of this tumor are similar to those of any other renal tumor, such as abdominal pain and hematuria.[1] Imaging examination, including CT and magnetic resonance imaging, shows large masses with solid and cystic components.[1] In the present case as well, the tumor was very large; the extensive retroperitoneal space allowed it to grow without oppressing the adjacent organs. Imaging studies do not have much diagnostic value for primary renal SS, and diagnosis always requires pathological evidence.[5] A recent study reported that fine needle aspiration biopsy cytology was useful for preoperative diagnosis,[4] but there is the risk of the fine needle causing metastasis of tumor cells via the blood.

SS can be histologically subclassified into biphasic and monophasic types.[6] The latter is characterized by epithelial cell or spindle cell components, particularly spindle cells, as was observed in the present case as well. Neoplasms with cellular atypia and frequent mitoses generally have a poor outcome. Poorly differentiated SSs present hyperchromatic, high-grade nuclei, and scanty cytoplasm that lack the bland spindle cells typical of monophasic SSs.[7] [Table 1] lists previous cases of such poorly differentiated SSs. A previous report mentioned that the monophasic type was difficult to distinguish from spindle cell sarcomas such as leiomyosarcoma, Wilms' tumors, and sarcomatoid renal cell cancer [1] and used immunohistochemical studies to confirm the pathological diagnosis. SSs usually stain positive for bcl-2, CD56, and vimentin, and focally for EMA, while they stain negatively for desmin, actin, S-100, CD34, and CD31.[1] The tumor in the present case stained positive for bcl-2 and EMA and focally positive for actin and CD10, while it stained negative for S-100, CK, and desmin. Unfortunately, no marker has been identified specifically for SS.[2] Molecular or cytogenetic analysis has also been used to confirm the pathological diagnosis of SS. Most of these neoplasms are considered to be associated with a unique chromosomal translocation, that is, t (x; 18) (p11.2;q11.2), which results in the fusion of SYT-SSX.[2] Although primary renal SS can therefore be confirmed by molecular detection of SYT-SSX fusion, only 4 of 15 cases of primary renal SS reportedly showed SYT-SSX fusion transcripts on molecular detection.[6]{Table 1}

Chemotherapy after surgical resection of primary renal SSs has been suggested as essential for extending patient life.[4] Although no specific chemotherapeutic target sites have been found for this neoplasm, high-dose ifosfamide-based protocols may be useful, given the chemotherapeutic sensitivity of some soft tissue sarcomas. In fact, complete remission after chemotherapy with doxorubicin and ifosfamide was noted in a previous case of renal SS.[8] Further, it has recently been reported that sorafenib inhibits the growth of SS cell lines in vitro by inhibiting the RAF/MEK/ERK signaling pathway,[9] and Basso et al. reported a case of SS in the left thigh with lung metastases that responded well to systemic chemotherapy (epirubicin plus ifosfamide) and sorafenib for secondary management.[9] As another treatment option, cellular immunotherapy administered via tumor-infiltrating lymphocytes may be effective. NY-ESO-1, a cancer/testis antigen, was reportedly expressed in 80% of patients with SSs, and a clinical trial revealed that adoptively transferred autologous T-cells transduced with a T-cell receptor against NY-ESO-1 mediated the regression of NY-ESO-1–positive SSs.[10] The current patient refused any further management after the operation, but we will continue follow-up.


Primary renal SS is rare and difficult to distinguish from other renal cell carcinomas. Early diagnosis-based solely on imaging studies without histopathological, cytogenetic, or molecular studies is very difficult. Although the prognosis of primary renal SS is generally poor, ifosfamide-based chemotherapy and based cellular immunotherapy after surgical resection may achieve curative effects.

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