BENIGN EPITHELIAL STRUCTURES ON THE SURFACE OF APPENDIXES

Reported here are five cases of rare and hitherto unreported adenomato id epithelial structures which occurred under the peritoneal surface o f appendix vermiformis, These epithelial structures consisted of matur e, smart non-branching, cystically dilated adenomatoid spaces lined by one or two layers of flat cells without atypia or mitoses. In two cas es these structures underwent focal squamous cell metaplasia. It is hy pothesized that these epithelial structures arise from the peritoneum. They should be especially distinguished from metastatic adenocarcinom a.