Serous Cystadenocarcinoma of Pancreas: A Rare Find

Abstract

Abstract Introduction/Objective Pancreatic cystic neoplasms comprise 1-2% of pancreatic lesions and most of these lesions are cystadenomas. Serous cystadenocarcinoma is an extremely rare but known malignant condition described in the literature and the diagnosis is restricted to cases with distant metastasis of tumor beyond the pancreas. Per WHO, cytologic atypia, vascular, perineural, and adjacent organ and lymph node involvement by direct spread are insufficient for the diagnosis of serous cystadenocarcinoma. Methods/Case Report We report an interesting case of serous cystadenocarcinoma of pancreas in a 55-year-old male with medical history of prostate cancer was found to have a 15 cm mass pancreatic tail suspicious for neuroendocrine tumor and 5 small hepatic lesions suspicious for metastasis. The patient underwent subtotal pancreatectomy and splenectomy, and wedge resection of liver lesions. On gross examination, a yellow cystic mass was present in the pancreatic tail measuring 13.2 cm in the maximum dimension. H&E slides from the pancreas and liver demonstrated a neoplasm composed of cystic and solid areas, within a background of fibrosis and focal hemorrhage. Cystic areas showed microcysts composed of cells with clear cytoplasm and round to oval bland nuclei. Solid areas demonstrated almost no microcysts but sheets and clusters of cells with clear to scant cytoplasm, oval to round nuclei, few areas of atypical hyperchromatic cells, and occasional mitosis. Very focal clusters and cords of neuroendocrine cells, constituting less than 5% of the tumor volume were also identified. Immunohistochemical stains demonstrated the neoplastic cells both in cystic and solid areas were positive for CK7, CK19, MUC6, and inhibin. Ki67 demonstrated an overall proliferation index of 3%. Chromogranin and synaptophysin were negative within the solid and cystic components of the tumor, however, showed positive staining within neuroendocrine foci. Neoplastic cells were negative for all other tested markers including beta-catenin, ER, Hep-par 1, HMB45, IMP3, MART-1, PAX-8, and trypsin. RB1 expression was retained within neoplastic cells. Results (if a Case Study enter NA) N/A. Conclusion The differentiation between benign and malignant serous cystadenoma both histologically and clinically may be very difficult as some cases of serous cystadenocarcinoma may not show overt cytologic atypia. The presence of metastasis, which most often occurs in the liver is required for the diagnosis of serous cystadenocarcinoma.