Rapidly Progressive Peritoneal Carcinomatosis Originating From Mucinous Appendiceal Adenocarcinoma: A Case Report.

Malignant neoplasms of the appendix are rare. These neoplasms can be further delineated into either colonic or cystic types. A cystic type appendiceal tumor is often referred to as an appendiceal mucocele due to its production of jelly-like mucus. Mucinous appendiceal adenocarcinoma (MAA) is a malignant appendiceal mucocele associated with nonspecific symptoms and often found incidentally when other abdominal work-up is performed. If the appendix ruptures, the peritoneal cavity and organs are coated with mucus-producing cells, leading to the complication pseudomyxoma peritonei (PMP). If found late in the disease progression, it can further develop into peritoneal carcinomatosis, which is typically treated with cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC). A 28-year-old male with no past medical history arrived at the emergency department for longstanding constipation. Upon workup, he was found to have stage IV MAA with dissemination into the peritoneal cavity leading to PMP and peritoneal carcinomatosis. The mucin in his abdominal cavity had proliferated and solidified to the point where CRS/HIPEC was unable to be performed. He received multiple rounds of palliative chemotherapy; however, it failed to shrink any tumors or lessen mucin burden in order to receive CRS/HIPEC.  This case demonstrates the importance of early detection of MAA. It also illustrates that even in healthy young adults, advanced peritoneal carcinomatosis may impede CRS/HIPEC from being performed. In the current literature, most patients with peritoneal carcinomatosis, unless contraindicated, are able to receive CRS/HIPEC.