Rectal cancer presenting with synchronous intraperitoneal spread of disease

There are differing definitions regarding what portion of the large intestine should be considered “rectum” as opposed to “colon.” The transition from intra- to extraperitoneal rectum results in potentially disparate patterns of spread for rectal cancer dependent on tumor location relative to the peritoneal reflection. Here we report the case of a 50-year-old woman with a mid to upper rectal adenocarcinoma who presented with a synchronous biopsy-proven tumor implant in the peritoneal cavity. Her case highlights issues of varying definitions of organ anatomy within the literature, the role of primary tumor localization within different compartments of the abdominopelvic cavity for predicting potential routes of tumor spread, and the implications for adjuvant therapies.