Synovial sarcoma in a 44-year-old woman located between the left rectus abdominis muscle and the aponeurosis of the transversus abdominis muscle, outside the peritoneal cavity.
A: Photograph of the sectioned gross specimen shows the synovial sarcoma with solid components (*) and hemorrhage (H).
B: Microscopically, a monotonous spindle cell lesion was seen with round to oval nuclei (hematoxylin and eosin stain, magnification 100x).