Solid Serous Cystadenoma of the Pancreas: A Case Report of 2 Patients Revealing Vimentin, β-Catenin, α-1 Antitrypsin, and α-1 Antichymotrypsin as New Immunohistochemistry Staining Markers

Solid serous cystadenoma (SCA) of the pancreas is a rare type of pancreatic solid tumors. Postoperative pathological evaluation is of particular importance for distinguishing solid SCA of the pancreas from other pancreatic solid tumors. Here we present 2 cases of solid SCA of the pancreas, both preoperatively diagnosed with pancreatic neuroendocrine tumors. One case had positive OctreoScan test. Surgical resections were done for both cases. Postoperative immunohistochemistry assays were conducted with marker panels for SCA and 2 types of pancreatic solid tumors, which were neuroendocrine tumor (pNET) and solid pseudopapillary tumor (SPT). Two cases showed typical staining patterns for SCA markers. Notably, both cases showed positivity for 4 SPT markers (vimentin, β-catenin, α-1 antitrypsin, and α-1 antichymotrypsin). Emphasis should be paid to those 4 new markers for future pathological diagnosis of solid SCA of the pancreas.