[Pancreatic adenocarcinoma:a case containing a cyst enclosing a dilated tubular gland duct].

This case report describes a 73-year-old woman with pancreatic adenocarcinoma who had undergone a colectomy for colorectal cancer in 1995 and a right mastectomy and axillary dissection for breast cancer in 2013. In January 2019, a tumor, approximately 20mm in diameter, was detected in the pancreatic body. It contained a cyst noted to have delayed perfusion towards the center on abdominal computed tomography. On T1-weighted magnetic resonance imaging (MRI), almost the entire tumor exhibited low intensity. On T2-weighted MRI, however, the tumor center displayed high intensity, the tumor wall displayed low intensity, and the outermost layer displayed high intensity. On endoscopic ultrasound, the tumor center displayed low echo density, the tumor wall had a slightly elevated echo density, and the outermost layer had a low echo density. A distal pancreatectomy was performed for a suspected metastatic pancreatic cancer, pancreatic neuroendocrine neoplasm, or invasive ductal carcinoma without tubular adenocarcinoma. Histopathological examination revealed that the tumor cells had formed atypical tubular gland ducts with a fibrous stroma in the background. The lesion differed from the histopathological findings of her previous colorectal and breast cancers, and it was ultimately diagnosed as a pancreatic ductal adenocarcinoma. The lumen of the cyst was covered with tumor cells identical to those of the atypical tubular gland ducts in the tumor parenchyma, suggesting that the cyst was a dilated tubular gland duct.