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Pancreatic ductal adenocarcinoma differs from other solid tumors with its unique immunosuppressive microenvironment and non-immunogenic feature. There are not many studies in the literature investigating the effect of these features on prognosis. To investigate the prognostic value of tissue-resident memory T cells, tumor microenvironment features, and tumor-associated immune cells in resected pancreatic ductal adenocarcinomas. Retrospective cross-sectional study. Of 138 patients diagnosed with pancreatic ductal adenocarcinoma between 2011 and 2018, 81 were included in the study. Specimens from operated patients were reassessed separately as peritumoral and intratumoral areas for tissue resident memory cells and tumor microenvironmental elements (tumor infiltrating lymphocytes, tumor stroma, CD204+ macrophages, PDL1+ immune cells). Disease-free survival and overall survival were defined from the date of operation to the date of recurrence and the date of first diagnosis to the date of death, respectively. If the patient was alive, the last visit date was taken into account. The median age at diagnosis was 63 (range: 40-78). The median follow-up period was 18.9 months (range: 1.4-80.4 months). Median overall survival was 23.7 months (1.4-80.4 months) and median disease-free survival was 10.8 months (1.4-74.4 months). Patients with higher intra-tumoral tissue-resident memory cell counts had a longer survival trend than those having lower values (25.6 months vs. 18 months, respectively, P = .84). According to microenvironmental evaluations, lower stromal score (defined as stroma having less desmoplasia and rich in cells) and presence of peritumoral Crohn’s-like inflammatory response were associated with higher survival (29.2 months vs. 19.7 months for low vs. high stromal scores, respectively, P = .16 and 30.2 months vs. 18.1 months for the presence of Crohn’s-like inflammatory response P = .13). Decreased survival was observed in tumors with increased CD204+ tumor-associated macrophages which were immunosuppressive elements of the microenvironment (12 months vs. 26.3 months for intra-tumoral assessment, P = .29). Tissue-resident memory T cells and other microenvironmental features may be prognostic in resectable pancreatic ductal adenocarcinomas. Further studies with larger cohorts are needed for validation.

Solitary fibrous tumor (SFT) has been increasingly reported in various anatomic sites. However, it is still extremely rare in the pancreas. Herein, we present the first series of primary pancreatic SFTs. Nine cases of primary pancreatic SFTs were analyzed. The mean age was 60 years (36 to 76 y) with no sex predilection. Six tumors were in the head, 3 were in the tail. On imaging studies, tumors were described as a hypervascular mass, 2 revealed cystic areas, and 3 were favored to be neuroendocrine tumors. On biopsy, 2 cases were diagnosed as atypical spindle cell tumor; one was misdiagnosed as suspicious for sarcoma, and another case as metastatic renal cell carcinoma. Two were diagnosed as low-grade sarcoma and low-grade stromal tumor on frozen sections. Grossly, tumors were well-demarcated with a median size of 4 cm (0.9 to 15 cm). Microscopically, they were composed of ovoid to spindle tumor cells with no significant mitotic activity and were arranged in alternating hypercellular and hypocellular areas. Staghorn-like vessels and entrapped pancreatic parenchyma were also detected within all tumors. Tumor cells revealed diffuse/strong nuclear STAT6 expression in 7 of 8, CD34 in 7 of 9, and bcl-2 in 4 of 4 tested cases. One tested tumor harbored NAB2-STAT6 fusion. Eight patients with available follow-up data were free of disease at a mean follow-up of 76 months (3 to 189 mo). SFT should be considered in the differential diagnoses of mesenchymal neoplasms of the pancreas. Immunohistochemical nuclear STAT6 expression is a characteristic feature of SFT. Primary pancreatic SFTs seem to have favorable biological behavior in our series.

“Eosinophilic cholecystitis” has been an elusive concept. Around 1050 consecutive cholecystectomies with chronic (CC, n = 895), subacute (SAC, n = 100), and acute cholecystitis (AC, n = 55) were reviewed for eosinophilic infiltration. Eosinophilic hot spots (>40 eosinophils/HPF) were seen in 63% of SAC and 35% of AC (vs. 6% of CC, p < 0.001). Eosinophils were mostly encountered in areas of wall thickening, revealing edema with early collagenization and young tissue-culture-type fibroblasts. However, in ten chronic cholecystitis patients (100 eosinophils/HPF) was noted. These ten cases, classified as “eosinophilic cholecystitis”, were analyzed further: The patients were relatively young (mean age = 43 years), with a 9:1 female:male ratio. None had blood eosinophilia/eosinophilia syndromes. Although one had ulcerative colitis, others did not have any autoimmune diseases. The mean gallbladder wall thickness was 3.5 mm (vs. 4.2 mm in ordinary CC). In conclusion, eosinophils are a part of especially subacute injuries in the gallbladder. They are typically condensed in the areas of healing and appear to signify a distinctive state of injury in which there are erosions leading to slow/sustained exposure of the mural tissues to the bile contents that induce chemical injury/recruit eosinophils. Eosinophilic cholecystitis is a very uncommon occurrence and appears to be an exaggerated response in allergic patients who are prone to recruit eosinophils in reaction to injury.

The Importance of Stroma and Stromal SMA Expression in Pancreatic Ductal Adenocarcinoma