RESUMO
Introduction and importance: Congenital peritoneal encapsulation (CPE) is a rare condition in which the small intestine is encased within a mesothelial-lined sac. The following case is an extremely rare description of the co-existence of both colon cancer and peritoneal encapsulation, highlighting the potential role of this co-existence in preventing the spread of metastases and tumor implantation. Case-presentation: A 60-year-old female was diagnosed with metastatic colon cancer. During the operation, a thin fibrous membrane was found covering the small intestine, which suggested CPE. The tumor was removed, and the additional membrane was totally excised. The patient is currently receiving chemotherapy for metastatic treatment and is in good health. Clinical discussion: CPE is a medical condition that results from abnormal peritoneal development, and it is often confused with other differential diagnoses resulting from inflammatory causes. It can occur at different ages and remains asymptomatic for the majority of cases. However, it can be a potential cause of bowel obstruction. An intraoperative diagnosis can easily differentiate the case. The co-existence with colon cancer has been described only once in the literature. Conclusion: Peritoneal encapsulation is a rare, mostly asymptomatic condition. However, it may play a protective role in preventing metastatic colon cancer from affecting the small intestine, thus potentially opening up new avenues for the treatment of cancer metastases.