Peritoneal leiomyosarcomatosis originating from gastrointestinal leiomyosarcomas: CT features.

PURPOSE: To evaluate the computed tomographic (CT) features of peritoneal leiomyosarcomatosis (PL) originating from gastrointestinal leiomyosarcoma and compare the CT features of primary gastrointestinal leiomyosarcomas between patients with and those without PL.

MATERIALS AND

METHODS

The authors reviewed the medical and surgical-pathology records and the CT scans of 89 patients with gastrointestinal leiomyosarcoma to determine the prevalence of PL. Also, the CT scans of the patients with PL were evaluated for the morphologic appearance of peritoneal lesions. The CT features of the primary tumors were compared between the patients with and those without PL. Student t and Fisher exact tests were performed.

RESULTS

Metastases were present in 39 patients. PL was seen in 25 patients. Other metastatic sites included liver in 26 patients, lymph nodes in 11, lungs in three, and bone in one. In the 25 patients with PL, CT findings included multiple discrete peritoneal nodules in 22 patients and massive peritoneal lesions in three. Smudged omental infiltration was combined with other findings in 10 patients. The sites of the peritoneal masses were mesentery in 18 patients, omentum in 11, paracolic gutters in 11, pelvic cavity in eight, perihepatic space in three, and perisplenic space in one. Four patients had ascites. There were statistically significant differences in size of primary tumor (mean diameter, 12.5 cm vs 9.2 cm) (P =.01) and prevalence of exophytic growth of primary tumor (P =.02) between the patients with and those without PL.

CONCLUSION

CT findings can indicate PL in the differential diagnosis. The prevalence of PL appears to be higher when it originates from large primary tumors.