Retroperitoneal enterogenous cyst combined with teratoma.

A 63-year-old man presented with left abdominal pain, abdominal distention, and black stool following emotional stress and strenuous exercise. CT examination revealed a large cystic mass in the left abdominal cavity, as well as the presence of a teratoma in the hepatogastric space and a descending duodenal diverticulum. Subsequently, he underwent surgical resection, and the pathological findings indicated that the cyst wall consisted of mucinous glandular epithelium and smooth muscle, displaying a structure similar to normal intestinal wall tissue. Furthermore, the cyst was lined with ciliated columnar epithelium, confirming the diagnosis of an isolated enterogenous cyst (EC). Due to the potential trauma associated with excising the EC, the patient did not undergo resection of the teratoma, especially given its proximity to a branch of the trunk abdominal artery.