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Pancreatic mixed acinar-neuroendocrine carcinomas are rare malignant tumors of the pancreas. They are composed histologically of both acinar and neuroendocrine cells. The pancreatic duct is known to be an important site of tumor growth for acinar cell carcinomas, neuroendocrine tumors, and intraductal tubulopapillary neoplasms. To the best of our knowledge, there has been only 1 report of a mixed acinar-neuroendocrine carcinoma growing into the pancreatic duct and no reports detailing imaging findings with this tumor. We here report a 69-year-old man who presented with worsening glycemic control. Multiphase contrast-enhanced computed tomography and magnetic resonance imaging revealed a well-circumscribed mass with poor contrast enhancement in the pancreatic tail region of the pancreatic duct. The intraductal mass showed diffusion restriction on magnetic resonance imaging. These imaging findings are consistent with the expansive, smooth-surfaced polypoid tumor of low vascularity and high cellularity that was diagnosed pathologically. Mixed acinar-neuroendocrine carcinomas should be included in the differential diagnosis of intraductal tumors of the pancreas with poor contrast enhancement and diffusion restriction.

Abstract Background Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors, but are the most common mesenchymal tumors of the gastrointestinal tract. The risk classification of GISTs is based on the tumor size, mitotic index, tumor site, and presence of tumor rupture. Recurrence in the very-low-risk group is extremely rare. We herein report a case of liver metastases 2 years after resection of a very-low-risk duodenal GIST. Case presentation A 57-year-old woman presented to the hospital for evaluation of melena. Esophagogastroduodenoscopy showed bleeding from the exposed blood vessels at the top of a submucosal tumor approximately 20 mm in size located in the second (descending) part of the duodenum, and the bleeding was controlled with electrocoagulation. A GIST was suspected, and the patient underwent wedge resection of the duodenum. The resected specimen contained a 16- × 12-mm (

Large-duct type pancreatic ductal adenocarcinoma (PDA) is a rare morphologic variant forming large duct elements. This case report, to our knowledge, is the first report of a large-duct type PDA with a “honeycomb” appearance resembling a serous cystic neoplasm (SCN) on CT and MRI. The patient is an 82-year-old woman who presented with upper abdominal pain. Dynamic contrast-enhanced CT revealed a multilocular cyst with honeycomb loculi, in which the cyst walls showed gradual enhancement. On T2-weighted MRI, the mass displayed inhomogeneous hyperintensity characterized by a honeycomb appearance with irregular and thick hypointense cyst walls. The patient underwent distal pancreatectomy; histopathological diagnosis was large-duct type PDA. Although the imaging features of large-duct type PDA may resemble those of SCN, this distinction between PDA and SCN is important because the treatment options are very different.