PANCREATIC CYSTIC ISLET-CELL TUMORS - CLINICAL AND PATHOLOGICAL FEATURES IN 2 CASES WITH CYST FLUID ANALYSIS

Cystic islet-cell tumors are rare neoplasms that may be confused with more familiar cystic pancreatic lesions, such as pseudocysts, serous c ystadenoma, and mucinous tumors. Analysis of aspirated cyst fluid for tumor markers (carcinoembryonic antigen [CEA], CA-125, and CA-15.3), e nzymes (amylase and lipase), viscosity, and cytology has been proposed as an aid to preoperative differential diagnosis. These tests will di stinguish mucinous from nonmucinous cysts and usually help in determin ing malignancy. However, cyst fluid parameters from rarer types of pan creatic cystic tumors have not been described. We report the clinical and pathologic features of two cystic islet-cell tumors including cyst fluid parameters in one of the cases. Two cases of cystic islet-cell tumors were identified by clinical history, histopathologic, and immun ohistochemical techniques. Cyst fluid was aspirated intraoperatively f rom one case and analyzed for CEA, CA-125, CA 15.3, insulin, amylase, viscosity, and cytology. Cyst fluid analysis showed low values for CEA , CA-125, and CA-15.3, low viscosity, and variable amylase content. Th is spectrum of findings is similar to that of serous cystadenomas. Cys t fluid cytologic examination was positive for neuroendocrine-type epi thelial cells and insulin levels were elevated, observations indicativ e of an islet-cell tumor. Analysis of fluid from cystic islet-cell tum ors may aid in the preoperative differentiation of these tumors from m ore common pancreatic cystic lesions. These findings represent the fir st report of the characteristics of the fluid in these uncommon tumors .