A 57-year-old man presented with acute epigastric pain. Computed tomography (CT) showed a hyperdense mass consistent with hematoma (Picture 1). The patient underwent laparotomy for hemostasis and was diagnosed with intraperitoneal hemorrhaging of unknown etiology. Two months after the laparotomy, CT revealed not only the mass (Picture 2, arrows) but also multiple nodules suspected of peritoneal dissemination (Picture 2, arrowheads) in the intraperitoneal cavity. Histopathology of the find-needle aspiration biopsy specimen revealed aggregates of atypical spindle cells (Picture 3). The presence of the SS18-SSX fusion gene was confirmed by fluorescence in situ hybridization (Picture 4). The tumor was not found outside the abdominal cavity. Finally, the patient was diagnosed with primary intra-abdominal synovial sarcoma, which, based on the CT and intraoperative findings at laparotomy, was hypothesized to have originated from the omentum. Upon the diagnosis of synovial sarcoma, the patient received palliative chemotherapy with doxorubicin. Synovial sarcoma is a soft tissue sarcoma characterized by the SS18-SSX fusion gene that typically develops in the extremities of adolescents (1). Intraperitoneal hemorrhaging from soft tissue sarcoma has been scarcely reported, although various solid tumors can cause intraperitoneal hemorrhaging.
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The authors state that they have no Conflict of Interest (COI).
References
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