Synovial Sarcoma of the Right Pelvis in a 40-Year-Old Woman with an Unusual Presentation: A Case Report

Introduction: A synovial sarcoma is a rare and aggressive soft tissue tumor which is commonly found in the lower extremity. It most commonly presents in young to middle-aged adults. The peak incidence occurs between the second and fifth decades. Recurrence of the tumor is uncommon. "nCase Presentation: This case was a 40-year-old woman who was referred because of a relatively rapid enlargement of the right buttock in a one month period after an intra-muscular injection. There was no pain or any other problem."nOn physical examination, prominency of the right buttock without definite mass or tenderness or ery-thema was noted. Ultrasonography revealed a heterogeneous mass of the right buttock without a definite border containing a cystic component. "nOn contrast enhanced CT scan a large 170×150×120 mm heterogenous dumble shaped solid cystic mass was seen in the right greater sciatic notch with involvement of the piriformis muscle accompanied with central necrosis and preservation of adjacent intermuscular fascia. Sclerosis of the right iliac wing with pressure erosion of the external border was noted. No significant adenopathy was detected. MRI revealed the same appearance only with a relative definite border."nAccording to the above-mentioned factors, round cell tumors, lymphoma, MFH, reticulo-cell sarcoma, neurofibrosarcoma and with less possibility deep abcess were our differential diagnoses. Due to the dumble shape appearance, neurofibrosarcoma was our first diagnosis. Biopsy revealed synovial sarcoma (a rare tumor) and partial resection was considered and the patient tolerated chemoradiotherapy. Lung CT scan showed no metastasis."nConclusion: Synovial sarcoma is a rare soft tissue tumor. The interesting point of this case was not only because of its rarity but also because of the unusual location of occurrence and rapid progression."nKeywords: Synovial Sarcoma, Pelvis, Sacrosciatic Notch