A case of pancreatic adenosquamous carcinoma with direct invasion to the gastrointestinal tract through the retention cyst wall: A rare case report

A 62-year-old man presented with a 7-cm cystic lesion with irregularly thickened cyst wall in contact with the pancreatic tail. The pancreatic tail was described as hypoechoic on endoscopic ultrasonography. The cyst subsequently increased rapidly to 13 cm, and surgery was performed. This revealed adenosquamous carcinoma in the pancreatic tail to have invaded the stomach and transverse colon along the cyst wall. The cyst was diagnosed as a retention cyst due to pancreatic tail tumor. Invasion of nearby organs by a pancreatic cancer via the retention cyst wall is very rare, but it is necessary to keep the potential for such progress in mind. We experienced a rare case with pancreatic adenosquamous carcinoma (PASC) that invaded nearby organs via the retention cyst wall. We need to account for possible invasion of the cyst wall and nearby organs in treatment of pancreatic cancer accompanied with a retention cyst or pseudocyst.image