Mesenteric pseudocyst of the transverse colon: unusual presentation of more common pathology.

A 72-year-old man presented to the hospital with a cyst in the abdominal cavity as the main finding obtained by abdominal CT. The cyst measured 13.5×9 cm and was located near the proximal wall of the body of the stomach. Endoscopic ultrasonography revealed that, the size of the cyst was 8.6×8.8 cm and that most of it was anechoic. However, partially heterogeneous and hypoechoic solid portions and a septum were detected. This cystic lesion was separated from the stomach wall and pancreas. Surgical resection was performed. The final histopathological test results showed that the cystic mass originated from the mesentery of the transverse colon, and the cyst was diagnosed as mesenteric pseudocyst because the cystic wall was composed of granulation tissue without lining epithelial cells.