Neoadjuvant therapy is increasingly used to control local tumor spread and micrometastasis of pancreatic ductal adenocarcinoma (PDAC). Pathology assessments of treatment effects might predict patient outcomes after surgery. However, there are conflicting reports regarding the reproducibility and prognostic performance of commonly used tumor regression grading systems, namely College of American Pathologists (CAP) and Evans’ grading system. Further, the M.D. Anderson Cancer Center group (MDA) and the Japan Pancreas Society (JPS) have introduced other grading systems, while we recently proposed a new, simple grading system based on the area of residual tumor (ART). Herein, we aimed to assess and compare the reproducibility and prognostic performance of the modified ART grading system with those of the four grading systems using a multicenter cohort. The study cohort consisted of 97 patients with PDAC who had undergone post-neoadjuvant pancreatectomy at four hospitals. All patients were treated with gemcitabine and S-1 (GS)-based chemotherapies with/without radiation. Two pathologists individually evaluated tumor regression in accordance with the CAP, Evans’, JPS, MDA and ART grading systems, and interobserver concordance was compared between the five systems. The ART grading system was a 5-tiered system based on a number of 40× microscopic fields equivalent to the surface area of the largest ART. Furthermore, the final grades, which were either the concordant grades of the two observers or the majority grades, including those given by the third observer, were correlated with patient outcomes in each system. The interobserver concordance (kappa value) for Evans’, CAP, MDA, JPS and ART grading systems were 0.34, 0.50, 0.65, 0.33, and 0.60, respectively. Univariate analysis showed that higher ART grades were significantly associated with shorter overall survival (p = 0.001) and recurrence-free survival (p = 0.005), while the other grading systems did not show significant association with patient outcomes. The present study revealed that the ART grading system that was designed to be simple and more objective has achieved high concordance and showed a prognostic value; thus it may be most practical for assessing tumor regression in post-neoadjuvant resections for PDAC.

A 45-year-old woman was found to have a pancreatic tumor by abdominal ultrasound performed for a medical check-up. Abdominal contrast-enhanced computed tomography showed a hypovascular tumor measuring 30 mm in diameter in the pancreatic tail. Endoscopic ultrasound-guided fine needle aspiration was performed. An extragastric growing gastrointestinal stromal tumor was thereby diagnosed preoperatively, and surgical resection was planned. Laparoscopic surgery was attempted but conversion to open surgery was necessitated by extensive adhesions, and distal pancreatectomy, splenectomy, and partial gastrectomy were performed. The histological diagnosis was an intra-abdominal desmoid tumor. A desmoid tumor is a fibrous soft tissue tumor arising in the fascia and musculoaponeurotic tissues. It usually occurs in the extremities and abdominal wall, and only rarely in the abdominal cavity. We experienced a case with an intra-abdominal desmoid tumor that was histologically diagnosed after laparotomy, which had been preoperatively diagnosed as an extragastric growing gastrointestinal stromal tumor. Although rare, desmoid tumors should be considered in the differential diagnosis of intra-abdominal tumors. Herein, we report this case with a literature review.

Diffuse nectin-1 expression in the CAFs of PDAC patients is associated with invasion, metastasis, and shorter survival.

Accessory spleens (ASs), ectopic splenic tissue at intrapancreatic and extrapancreatic sites, rarely contain epidermoid cysts. Our aim was to analyze the incidence of epidermoid cysts in ASs and perform an immunohistochemical analysis of its epithelial lining. We included in the study 148 ASs from 135 patients, for which pathological data were available. Eleven were intrapancreatic ASs (IPASs) and 137 were extrapancreatic ASs (EPASs). Six of the eleven (55%) IPASs contained epidermoid cysts, but they were not detected in EPASs. Immunohistochemical analysis showed that both the superficial/luminal and basal layer of the epithelial lining of epidermoid cysts in IPASs are negative for MUC2, MUC5AC, MUC6, WT-1, calretinin, thrombomodulin, uroplakin-II, and uroplakin-III. The superficial/luminal layer was positive for MUC4, CK7, and CA19-9 in all cases (100%), for CEA and HBME-1 in three cases (50%), and for MUC1, CK5/6, and CK20 in two cases (33%). The superficial/luminal layer was negative for p63 and D2-40 in all cases. The basal layer was positive for MUC1, CK5/6, p63, and HBME-1 in all six cases (100%), for CK7 and D2-40 in two cases (33%), and for CEA in one case (17%). The basal layer was negative for MUC4, CK20, and CA19-9 in all cases. Epidermoid cysts are a characteristic feature of IPASs but not of EPASs. Immunohistochemical analysis showed that the epithelial lining of epidermoid cysts in IPASs has a mixed character of glandular, squamous, mesothelial, and urothelial epithelium.

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