Presentation
Left sided chest mass incidentally found on physical examination.
Patient Data
Coronal and Axial CTs demonstrate a large arterial-enhancing, partially calcified left-sided thoracoabdominal wall mass displacing the diaphragm and inferior left 9th through 12th ribs. Part of the mass is visualized invading the abdominal wall between the left 10th and 11th ribs. Additional smaller similar mass is visualized anteriorly.
Tc-99 MDP bone scan demonstrating heterogenous radiotracer uptake within the large left sided thoraco-abdominal wall mass. No additional pathologic radiotracer uptake is visualized.
Pathology report from open biopsy:
The left chest wall mass biopsy sections contain a cellular neoplasm with solid sheet-like areas of mostly small to medium-sized monotonous round to ovoid tumor cells, resembling a small round blue cell tumor. Conspicuous blood vessels with focal hemangiopericytoma-like branching are seen in the background. Intermittent coarse calcifications are also seen within the tumor. The tumor cells are positive for SS18-SYT (strong and diffuse), EMA (patchy, weak to moderate intensity), CD99 (patchy, weak to moderate intensity), synaptophysin (patchy, weak intensity) and CD56 (weak to moderate intensity). Still, they are negative for pan-cytokeratin AE1/AE3, SMA, desmin, myogenin, MyoD-1, SOX10, CD20 and CD3.
Conclusion
The histologic findings and immunoprofile are diagnostic for synovial sarcoma. The SS18-SYT (SS18-SSX) immunostain is a highly sensitive and specific marker for synovial sarcoma.
Case Discussion
This patient presented to an annual well-child examination and the left chest wall mass was felt on palpation during the scoliosis examination.
An open biopsy was performed which demonstrated synovial sarcoma (grade 2). Neoadjuvant radiotherapy and chemotherapy were initiated. Surgical resection was then performed in addition to multiple pleural lesions and nodules within the dependent portions of the left upper and lower lung lobes. In addition, surgical excision of the inferior left ribs was performed with diaphragm reconstruction. The patient then continued on adjuvant chemotherapy due to the risk of recurrence.
CO-AUTHORS: Bianca Vescio, Nadim Abu-Hashem, MD
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