Objective: To observe clinical and pathological features of pancreatic solid-pseudopapillary tumor (SPPT), and to find some useful immunohistochemical methods for its differential diagnosis.
Methods: The clinical features of 14 SPPT patients were obtained. Each case underwent microscopic observation and immunohistochemical staining. The primary antibodies were CgA, Syn, E-cadherin, beta-catenin and Cyclin D1. These results were compared with 5 pancreatic well-differentiated tumors and well-differentiated carcinomas (WET/WEC).
Results: SPPT mainly involved young women, and the head of pancreas was the commonest location. Tumors were always in solid and cystic gross appearance. Although the tumor's borderlines seemed clear, focal infiltrations could often be identified. The histological features of SPPT were similar in some aspects to those of WET/WEC, especially the solid pattern of WET/WEC. Both of them could express CgA and Syn. But all SPPTs lost E-cadherin membranous signals, and even had some nuclear signals(5/14), while all WET/WECs remained the same staining pattern with normal pancreas cells. beta-catenin positive signals in SPPTs were located both in nuclei and plasmas. WET/WECs' positive signals were all in membranes and plasmas, but negative ones in nuclei. Perinuclear dot-like signals could also be seen in the majority cells, which were similar to normal islet cells' staining pattern. SPPTs' nuclear positive rates of Cyclin D1 were usually more than 70% (12/14). WET/WECs' rates were all lower than 30%.
Conclusion: Comprehensive analysis of patients' clinical, pathological features and immunohistochemistry results, including E-cadherin, beta-catenin and Cyclin D1, was helpful to the diagnosis of SPPT and its differential diagnosis of WET/WEC.