Synovial sarcoma mimicking desmoplastic small round-cell tumor: Critical role for molecular diagnosis

Background. The identification of recently described nonrandom chromosomal defects specific for various small round-cell and spindle-cell sarcomas can eliminate diagnostic uncertainty arising from the clinical and histopathol ogic overlap of soft tissue neoplasms. Methods. A 26-year-old man presented with bulky abdominal-pelvic disease. Immunohistochemical and molecular stu dies on tumor were performed. Treatment was instituted using cycles of high -dose cyclophosphamide (4,200 mg/m(2)) with doxorubicin (75 mg/m(2)). Resul ts. Clinical findings pointed to desmoplastic small round-cell tumor. The t umor was histologically undifferentiated and immunoreactive for vimentin bu t negative for other markers. Reverse transcriptase-polymerase chain reacti on revealed the SYT/SSX2 fusion transcript of the synovial sarcoma t(X;18) chromosomal rearrangement. The high-dose chemotherapy, plus surgery, achiev ed a complete remission, but recurrent disease emerged 13 months from diagn osis. Conclusions. This clinically unique case of synovial sarcoma highligh ts how the use of now readily available molecular techniques will allow mor e accurate appraisals of the incidence and anatomic distribution of soft ti ssue neoplasms-information that bears upon pathogenesis and treatment. This case confirms the utility of high-dose alkylator-based therapy for synovia l sarcoma. It also demonstrates that with nonlocalized solid tumors, the er adication of minimal residual disease remains an elusive goal. One alternat ive involves immunologic attack against markers derived from tumor-specific chromosomal defects such as those found in our patient. Med. Pediatr. Onco l. 32: 97-101, 1999. (C) 1999 Wiley-Liss, inc.