Right psoas muscle/aortoiliac groove recurrence: an unusual anatomic site for progression of epithelial tumors of the appendix.

Appendiceal carcinoma is a rare disease with low malignant potential. The resection site and the peritoneal cavity are the most common sites of tumor relapse. Despite extensive peritoneal involvement, the presence of regional lymph nodes and hematogenous metastases is exceptional. We report four cases of appendiceal carcinoma metastatic to the right psoas muscle/aortoiliac region and hypothesize regarding the mechanisms of dissemination. We use our experience with this unusual condition to make recommendations regarding treatment.