Survival Outcome and Prognostic Factors for Pancreatic Acinar Cell Carcinoma: Retrospective Analysis from the German Cancer Registry Group

Background: Pancreatic acinar cell carcinoma (PACC) is a distinct type of pancreatic cancer with low prevalence. We aimed to analyze prognostic factors and survival outcome for PACC in comparison to pancreatic ductal adenocarcinoma (PDAC), based on data from the German Cancer Registry Group. Methods: Patients with PACC and PDAC were extracted from pooled data of the German clinical cancer registries (years 2000 to 2019). The distribution of demographic parameters, tumor stage and therapy modes were compared between PACC and PDAC. The Kaplan–Meier method and Cox regression analysis were used to delineate prognostic factors for PACC. Propensity score matching was used to compare survival between PACC and PDAC. Results: There were 233 (0.44%) patients with PACC out of 52,518 patients with pancreatic malignancy. Compared to PDAC, patients with PACC were younger (median age 66 versus 70, respectively, p < 0.001) and the percentage of males was higher (66.1% versus 53.3%, respectively, p < 0.001). More patients were resected with PACC than with PDAC (56.2% versus 38.9%, respectively, p < 0.001). The estimated overall median survival in PACC was 22 months (95% confidence interval 15 to 27), compared to 12 months (95% confidence interval 10 to 13) in the matched PDAC cohort (p < 0.001). Surgical resection was the strongest positive prognostic factor for PACC after adjusting for sex, age, and distant metastases (hazard ratio 0.34, 95% confidence interval 0.22 to 0.51, p < 0.001). There was no survival benefit for adjuvant therapy in PACC. Conclusions: PACC has overall better prognosis than PDAC. Surgical resection is the best therapeutic strategy for PACC and should be advocated even in advanced tumor stages.

Clinical Characteristics of Resected Acinar Cell Carcinoma of the Pancreas: A Korean Multi-Institutional Study

Given the rare incidence of pancreatic acinar cell carcinoma (PACC), its post-resection clinical outcomes remain unclear. Treatment strategies for PACC have relied on those of pancreatic ductal adenocarcinoma (PDAC). The present study retrospectively investigated clinicopathologic characteristics of resected PACC registered in the Korea Tumor Registry System Biliary Pancreas database. Among 59 patients with a mean age of 59.2 years and a male predominance (83.1%), 43, 5, 7, and 4 had pure PACC, ductal differentiations, mixed neuroendocrine carcinomas, and intraductal and papillary variants, respectively. The mean tumor size was 4.6 cm, consisting of eight at T1, 26 at T2, and 25 at T3 stages. Metastasis to regional lymph node was identified in 15 (25.4%) patients. Thirty-one (52.5%) patients received adjuvant therapy. Five-year survival rate was 57.4%. The median survival was 78.8 months. In survival comparison according to the stage with AJCC system, N stage (lymph node metastasis), but not T stage, showed significant differences (p = 0.027). Resected PACC appeared to have clinical outcomes distinct from those of PDAC in this nationwide study. Therefore, large-scale multinational studies are needed to overcome the rarity of PACC and to establish an appropriate treatment strategies and staging system.

Carboxypeptidase A1 (CPA1) immunohistochemistry is highly sensitive and specific for acinar cell carcinoma (ACC) of the pancreas

Introduction/Objective Introduction: Carboxypeptidase A1 (CPA1) is a zinc metalloprotease which is produced in pancreatic acinar cells and plays a role in cleaving C-terminal branched-chain and aromatic amino acids from dietary proteins. This study assessed the utility of immunohistochemical CPA1 staining for diagnosing pancreatic acinar cell carcinoma. Methods/Case Report Methods: A total of 15,680 tumor samples from 132 different tumor types and subtypes as well as 8 samples each of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format. Results (if a Case Study enter NA) Results: CPA1 was strongly expressed in acinar cells of all normal pancreas samples but not in any other normal tissues. CPA1 immunostaining was detected in 100% of 11 pancreatic acinar cell carcinomas and one mixed acinar endocrine carcinoma (MAEC), but absent in 449 pancreatic ductal adenocarcinomas, 75 adenocarcinomas of the ampulla of Vater, and 11,739 other evaluable cancers from 128 different tumor entities. A weak to moderate diffuse staining of epithelial and stromal cells of cancer tissues immediately adjacent to non-neoplastic pancreatic acinar cells often occurred and was considered to be caused by diffusion of the highly abundant CPA1 from normal acinar cells that may have suffered some autolytic cell damage. Conclusion Our data show that CPA1 is a highly sensitive and largely specific marker for normal and neoplastic pancreatic acinar cells. CPA1 immunohistochemistry greatly facilitates the otherwise often difficult diagnosis of pancreatic acinar cell carcinoma.

Role of CD200 in the Detection of Nonhematologic Neoplasms by Routine Flow Cytometry Analysis

Objectives While flow cytometry is routinely used in the diagnostic work-up of hematolymphoid malignancies, its role in identifying non-hematolymphoid neoplasms is controversial. While a diagnosis of “non-hematolymphoid process” may be suggested by flow cytometry, typically, CD45-negative entities are not further characterized by their immunophenotypic profile. Some markers, such as CD56, have been well documented in non-hematolymphoid malignancies, such as high-grade neuroendocrine carcinomas (Stacchini, et al, 2018; Bryson et al, 2002). Other cell surface markers that are routinely studied with flow cytometry panels, such as CD200, are less well-described in the literature with regards to their presence/absence in non-hematolymphoid processes. We examined all flow cytometry cases from our institution over a 5-year period to identify trends in the immunophenotypes of non-hematolymphoid malignancies that were known to be CD45-negative and CD56-positive by flow cytometry. Methods We examined 3634 flow cytometry cases (2015-2020) and identified non-hematolymphoid cases based upon lack of CD45 expression. After excluding multiple myeloma cases from the CD45-negative entities, we were left with 19 CD45-negative cases. Chart review of these cases confirmed them as non-hematolymphoid by concurrent surgical pathology/cytopathology studies. Of these 19 cases, 2 were excluded because CD56 was not evaluated. Results Of the 17 CD45-negative/CD56-positive cases, 16 showed CD200 positivity (94%). Of these CD200-positive cases, 10 were ultimately diagnosed as small cell carcinoma (59%), 1 was diagnosed as Merkel cell carcinoma (6%), 1 was diagnosed as melanoma (6%), 1 was diagnosed as poorly-differentiated carcinoma (6%), 1 was diagnosed as Ewing-like sarcoma (6%), and 2 were unclassified further (12%). The single CD200-negative case was diagnosed as poorly-differentiated acinar cell carcinoma (6%). All cases of small cell carcinoma that were evaluated by flow cytometry showed expression of CD200 and CD56. Conclusions Our findings suggest that in CD45-negative/CD56-positive non-hematolymphoid malignancies, particularly small cell carcinoma, CD200 is frequently positive. CD200 was also found to be positive in rare cases of other non-hematolymphoid malignancies within the differential diagnosis of small round blue cell tumors. These findings indicate that CD200 may be a useful marker in suggesting the possibility of small cell carcinoma in non-hematolymphoid specimens that are evaluated by flow cytometry.