Clinicopathologic Study of 62 Acinar Cell Carcinomas of the Pancreas

Abstract

Acinar cell carcinoma (ACC) of the pancreas is a very rare tumor that has various morphologic features, which may give rise to diagnostic difficulties. Because of its rarity, many clinicopathologic characteristics remain to be further elucidated, and prognostic factors are yet to be well established. With the aim of better characterizing this carcinoma and searching for prognostic indicators, we collected 62 ACCs and investigated the following parameters: site, size, local infiltration, node and distant metastases, architectural pattern, nuclear atypia, presence of necrosis, lymphovascular and perineural invasion, proliferation, BCL10, trypsin, carboxyl ester lipase, amylase, lipase, PDX1, cytokeratin 19 (CK19), CK7, p53, and β-catenin expression. Twelve cases showing >30% of endocrine cells were reclassified as mixed acinar-neuroendocrine carcinomas, whereas 1 tumor was reclassified as a mixed ductal-acinar carcinoma and was excluded from the statistical prognostic evaluations. BCL10 and trypsin were the most reliable immunohistochemical markers, whereas amylase and lipase were not. Surgery was statistically correlated with a better prognosis (P=0.0008). Among resected tumors there was no difference in survival between ACCs and mixed acinar-neuroendocrine carcinomas, and factors that significantly correlated with poor prognosis were size >6.5 cm (P=0.004), lymph node (P=0.0039) and distant (P=0.008) metastases, and UICC stage (P=0.009). Stage was the only independent prognostic factor at multivariable analysis, and the best prognostic discrimination was observed on grouping together stages I and II and grouping together stages III and IV, suggesting a simplification of the UICC staging for such cancers. In addition, vascular and perineural invasion and CK19 and p53 expression showed a trend for poor prognosis, not reaching statistical significance.

Acinar cell carcinomas of the pancreas: a molecular analysis in a series of 57 cases

“…As PACs may not only display a mixed acinar and neuroendocrine differentiation but rarely may also contain ductal elements [4,8,11], we compared the CGH findings in PACs with those previously reported in PDACs and PNENs. This revealed some cytogenetic overlap between PACs, PDACs, and PNENs, including, among others, gains of 7 and 20q, as well as loss of 6q.…”

“…PACs are usually solid tumors, composed of cells expressing trypsin and other pancreatic enzymes [4,8]. Rare cystic variants are acinar cell cystadenocarcinomas [9] and acinar cell carcinomas containing substantial (>30 %) proportions of cells showing neuroendocrine and/or ductal differentiation [8,10,11].…”

“…Few published, mostly small, series have shown that mutations that are common in pancreatic ductal adenocarcinoms (PDACs), i.e., K-RAS, p16, and SMAD4/DPC4, are rare in PACs [12][13][14][15][16][17][18][19]. Alterations of the β-catenin/adenomatous polyposis coli (APC) pathway have been reported in a subset of PACs [8,12,19,20], paralleling findings in pancreatoblastoma [21]. An involvement of the β-catenin/APC pathway in a significant subset of PACs was supported by a more recent study, in which APC loss and hypermethylation were found in up to 56 % of PACs, by far outnumbering APC mutations [20].…”

Acinar Cell Carcinoma of the Pancreas: Overview of Clinicopathologic Features and Insights into the Molecular Pathology

“…Males are more commonly affected with a male/female ratio of 2:1 (2–4). In the majority of cases presenting symptoms are non-specific and include abdominal pain, weight loss, vomiting, and nausea, which are related to tumor growth and/or metastatic spread.…”

SALL4 is expressed in pancreatic acinar cell carcinoma

“…They are frequently encapsulated though invasion of tumor through the capsule is common. Grossly, the tumors can invade locally into adjacent organs including duodenum, mesenteric vessels, stomach, kidney, peritoneum, and spleen [22] .…”