[Clinicopathologic characterisitics of pancreatic acinar cell carcinomas]

Objective: To investigate clinical, pathological and immunohistochemical features of pancreatic acinar cell carcinoma. Methods: A retrospective review of surgical and pathological databases between 2011 and 2016 at PLA General Hospital was collected and 14 cases of acinar cell carcinoma (ACC) of the pancreas were identified. EnVision immunohistochemistry was used to detect the expression of Trypsin, bcl-10 and cytokeratin(CK) proteins. Results: The patients included nine cases of pure ACC, 3 cases of mixed acinar ductal carcinoma, 1 case of mixed acinar-neuroendocrine carcinoma and acinar-ductal-neuroendocrine carcinoma, respectively. Tumors involved different anatomic locations of the pancreas, including eight involving the head of pancreas, four in the body and tail, one in the uncinate process and one in a heterotopic pancreas. Two patients had lymph node and liver metastases before surgery. Microscopically, the tumor was hypercellular with less fibroblastic proliferation and tumor cells arranged in acinar or solid pattern. The well differentiated tumor cells showed eosinophilic, granular cytoplasm with single prominent nucleoli, while the poorly differentiated tumor cells tended to grow in solid sheets. Immunohistochemically, the tumor cells were positive for pan-cytokeratin (14/14), Trypsin (12/14) and bcl-10 (11/14). Stains for CK7 and CK19 were negative (11/14 and 3/4). According to the pTNM staging, there were 7 cases at stageⅠ, 3 at stage ⅡA, 3 at stage Ⅲ and 1 at stage Ⅳ. With average postoperative follow-up of 6-58 months, the median disease-free survival time was 16 months. Conclusions: Pancreatic acinar cell carcinoma is a rare and relatively indolent malignant tumor with characteristic histopathological and immunohistochemical features. Accurate pathological diagnosis plays an important role in patients' treatment and evaluation of prognosis.