Primary monophasic synovial sarcoma of the cervical esophagus confirmed by detection of the SS18-SSX2 fusion transcripts: case report and literature review

BACKGROUND: Synovial sarcoma (SS) of the esophagus is extremely rare. Because of the microscopic features of SS, the monophasic type can easily be misdiagnosed as other spindle cell tumors. Here, we present the first case of a primary SS of the esophagus in the presence of SS18-SSX2 fusion transcripts. CASE PRESENTATION: A 47-year-old Japanese woman was initially diagnosed with thyroid papillary carcinoma in the left lobe and leiomyoma of the cervical esophagus and subsequently underwent left thyroid lobectomy and enucleation of the esophageal tumor. Four years after the first surgery, the esophageal tumor recurred. Endoscopic biopsy of the tumor revealed atypical cell proliferation with spindle cell features and mitoses. Immunohistochemistry showed focal positivity for bcl-2 and HHF35. Furthermore, the presence of SS18-SSX2 fusion transcripts was confirmed by reverse transcription-polymerase chain reaction analysis, using a paraffin-embedded tumor specimen. Therefore, the tumor was diagnosed as monophasic SS of the cervical esophagus. We re-evaluated the surgical specimen enucleated 3 years previously, which was initially diagnosed as leiomyoma, and the diagnosis of SS was confirmed. The patient underwent cervical esophagectomy with isolated jejunal interposition reconstruction. Three years after the second surgery, SS recurred in the distal anastomotic site between the jejunum and the esophagus, and the patient underwent thoracoscopic esophagectomy with gastric conduit reconstruction. The pathological grade of the lesion worsened with every recurrence. CONCLUSIONS: Monophasic SS can be difficult to discriminate from other spindle cell tumors based on microscopy alone, and molecular analysis could be useful for confirming the precise diagnosis of monophasic SS.