INTRADUCTAL ONCOCYTIC PAPILLARY NEOPLASMS OF THE PANCREAS

We describe the clinical and pathologic features of II intraductal onc ocytic papillary neoplasms of the pancreas, a hitherto unrecognized tu mor. The patients were six men and five women, and most of the tumors were in the head (head: body/tail = 8:3). The mean patient age was 62 (range, 39-78), and the average tumor size was 6 cm. Grossly the tumor s exhibited mucin-filled cysts containing nodular papillary projection s. Dilated ducts communicating with the main tumor were sometimes note d. Microscopically the cystic structures appeared to represent dilated ducts containing intraductal tumor. The tumors were characterized by variably complex, arborizing papillary structures. The papillae had th in, delicate fibrovascular cores with focal myxoid changes and were li ned by stratified oncocytic cells. Goblet cells and intraepithelial mu cin-containing lumina were present, the latter resulting in a characte ristic cribriform pattern. The exuberance of the epithelial proliferat ion varied from case to case and between different regions within indi vidual tumors; solid sheets of cells were often identified. Although t he degree of cytologic atypia was not generally severe, the complexity of the architecture justified a designation of intraductal oncocytic papillary carcinoma in 10 of the 11 cases. In nine cases the tumor was entirely intraductal; one case exhibited focal microinvasion and anot her showed widespread invasive carcinoma, the invasive elements appear ing cytologically similar to the intraductal papillary components. The oncocytic cells stained positively with phosphotungstic acid hematoxy lin and Novelli stains. Immunohistochemically, all cases stained posit ively for B72.3, and five cases showed focal, weak luminal membrane st aining for carcinoembryonic antigen. Ultrastructurally many of the cel ls were packed with mitochondria, and mucin was also identified. Seven patients were alive and free of tumor from 1 month to 3 years (averag e, 1 year) after resection. Two patients died postoperatively. The rem aining two patients died with no evidence of disease at 2.5 and 5 year s, the latter following a recurrence at 2.5 years. We conclude that in traductal oncocytic papillary neoplasm is a distinctive pancreatic tum or that is usually intraductal but may develop invasive carcinoma and should be treated with complete resection.