Pathological complete response with FOLFIRINOX therapy for recurrence of pancreatic acinar cell carcinoma.

Pancreatic acinar cell carcinoma (PACC) is a very rare subtype of pancreatic cancer. Due to small number of patients, no standard chemotherapy protocol has been established. We experienced an extremely rare case of PACC with liver metastasis that showed a pathological complete response after modified FOLFIRINOX (mFFX) therapy. A 42-year-old man who underwent distal pancreatectomy for an 80 mm tumor at the pancreatic tail 3 years ago was referred to our hospital in September 2017 for the treatment of a recurrent liver tumor. Percutaneous biopsy revealed an acinar-neuroendocrine carcinoma, similar to the surgical specimen. He received eight cycles of irinotecan plus cisplatin chemotherapy. However, the tumor increased in size, and treatment was switched to mFFX therapy. The tumor in the liver shrank remarkably after nine cycles of mFFX therapy. Conversion surgery was selected, and the patient underwent hepatic left and caudate lobectomy 8 months after administration of mFFX. The resected specimen showed no viable tumor cells, indicating a pathological complete response. The histological diagnosis was reconsidered, and PACC was finally diagnosed via an additional immunohistological review. The patient has remained well with no recurrence for 6 years after surgery. This study is the first to report a case of pathological complete response with mFFX therapy for the recurrence of PACC.

A Case of Cystic Retroperitoneal Dedifferentiated Liposarcoma Diagnosed by Percutaneous Image-Guided Biopsy.

Introduction: Dedifferentiated liposarcoma (DDLP) was initially defined as a tumor containing differentiated liposarcoma and distinct regions of nonlipogenic spindle cell or pleomorphic sarcoma. Retroperitoneal liposarcomas feature a characteristic appearance with a predominantly fatty component, and cystic liposarcomas are rare. We describe a case of retroperitoneal DDLP predominantly consisting of multilocular cysts. Case Presentation: A 77-year-old man previously visited a doctor because an echo scan unexpectedly revealed an abdominal tumor. Contrast computed tomography (CT) disclosed a large multilocular cystic tumor spanning from the left upper abdomen to the retroperitoneum, and poorly marginated soft tissue structures were present around the abdominal aorta, inferior vena cava, pancreas, mesentery, and left kidney. CT also revealed a right lung mass. The soft tissue structures in the retroperitoneal cystic tumor and right lung mass were strongly enhanced on 2-deoxy-2-[fluorine-18] fluoro-d-glucose positron emission tomography, suggesting a malignant retroperitoneal tumor and lung metastasis. CT-guided percutaneous biopsy targeting the left perirenal soft tissue structure was performed, and the tumor was diagnosed as DDLP. Lung metastasis was present, and the retroperitoneal tumor surrounded multiple organs. Therefore, the tumor was not suitable for surgical resection but it was indicated for chemotherapy based on multidisciplinary discussion. Conclusion: We experienced a case of retroperitoneal cystic DDLP diagnosed by percutaneous image-guided biopsy and treated appropriately based on the pathological diagnosis.

Liver metastasis composed of pure squamous cell carcinoma component from pancreatic pure ductal adenocarcinoma: a case report.

BACKGROUND: Liver metastasis of pure squamous cell carcinoma (SCC) from pancreatic ductal adenocarcinoma has not been previously reported. CASE PRESENTATION: A 66-year-old man underwent a computed tomography scan 3 years after surgery for pancreatic head cancer, and the scan revealed a mass lesion in the right lobe of the liver. A liver tumor biopsy was performed, and SCC was diagnosed. Whole sections of the pancreatic head cancer were re-evaluated, but no areas of SCC-like differentiation were identified. Although the pathology differed between the pancreas and liver, metastasis of adenosquamous carcinoma was considered. Three courses of gemcitabine plus nab-paclitaxel were administered to treat the liver metastasis of pancreatic cancer, but no response was attained. Therefore, primary SCC of the liver was considered and hepatic resection was performed. The tumor had invaded the diaphragm, and S5/6 partial hepatic resection with right diaphragm resection was performed. Pathological examination showed pure SCC of the liver, which differed from the pancreatic cancer. KRAS mutations were evaluated in the pancreatic and liver tumor specimens, and Q61R mutation was identified in both specimens. This pure SCC of the liver was diagnosed as metastasis from pancreatic cancer not by histology but by genetic analysis. CONCLUSIONS: This is the first reported case of pure SCC liver metastasis from pancreatic cancer without a squamous cell component in the primary tumor. Evaluation of KRAS mutations in both specimens was useful for diagnosis.

Clinicopathologic Features and Genetic Alterations in Mixed-Type Ampullary Carcinoma.

Mixed-type ampullary carcinoma is a subtype that combines intestinal-type (I-type) and pancreatobiliary-type (PB-type) lesions, but few studies have examined its clinicopathologic features and genetic alterations. The differences in genetic alterations between mixed type and other subtypes, as well as the genetic differences between I-type and PB-type lesions in the mixed type, remain unclear. In this study, we compared the clinicopathologic features and prognosis of 110 ampullary carcinomas classified by hematoxylin and eosin and immunohistochemical staining as follows: 63 PB-type, 35 I-type, and 12 mixed-type carcinomas. A comparative analysis of genetic mutations by targeted sequencing of 24 genes was also performed in 3 I-type cases, 9 PB-type cases, and I and PB-type lesions of 6 mixed-type cases. The mixed subtype had a poorer prognosis than the other subtypes, and there was also a similar tendency in the adjuvant group (n = 22). A total of 49 genetic mutations were detected in all 18 lesions for which genetic alteration was analyzed. No genetic mutations specific to the mixed type were found, and it was not possible to determine genetically whether the mixed type had originally been I or PB type. However, 5 of 6 cases had mutations common to both I and PB-type lesions, and additional mutations were found only in either I or PB-type lesions. In support of this, the mixed type more frequently exhibited genetic heterogeneity intratumorally than the other subtypes. Mixed-type tumors are histologically, immunohistochemically, and genetically heterogeneous, and this heterogeneity is associated with poor prognosis and may affect treatment resistance.

Ampullary Neuroendocrine Neoplasm: Clinicopathological Characteristics and Novel Endoscopic Entity.

BACKGROUND: Neuroendocrine neoplasms of the ampulla of Vater (ampullary NEN) have features of both gastrointestinal and pancreato-biliary (PB) NEN. However, the limited number of studies examining ampullary NEN makes it difficult to clarify their unique characteristics. This study aimed to elucidate the clinical characteristics of ampullary NEN. METHODS: We enrolled 162 patients with PB-NEN diagnosed at Kyushu University Hospital between 2011 and 2020. Clinical features, pathological diagnoses, treatments, and prognoses were retrospectively analyzed. We also compared ampullary NEN with pancreatic NEN (PanNEN). RESULTS: We analyzed 10 ampullary NEN cases and 149 PanNEN cases. The ampullary NEN cases consisted of 4 cases of neuroendocrine tumor Grade 1 (NET G1), 1 NET G2 (Grade 2), and 5 neuroendocrine carcinomas (NECs). The incidences of NEC and cholangitis were significantly higher in ampullary NEN than in PanNEN. All ampullary NETs had a submucosal tumor-like appearance, as identified by endoscopic ultrasound-guided fine needle aspiration. We treated small NET G1 (<10 mm) with endoscopic papillectomy and large NET G1 with pancreaticoduodenectomy. There were no cases of recurrence after resection. All ampullary NECs presented with the characteristic endoscopic finding of a "crater sign" similar to deep-mining ulcers seen in gastric malignant lymphoma. Four cases underwent surgical resection, and 1 case was unresectable. Two patients who underwent multidisciplinary treatment were maintained without recurrence for over 2 years. CONCLUSIONS: Endoscopic findings showed identifiable distinctions between ampullary NETs and NECs.

MR Prediction of Malignant Switch With the Cyst Fluid's T2 Value in Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Preliminary Study.

BACKGROUND/AIM: We investigated whether the malignant switch of intraductal papillary mucinous neoplasm (IPMN) of the pancreas can be predicted by using the T1ϱ, T2, and apparent diffusion coefficient (ADC) values of cyst fluid. PATIENTS AND METHODS: We retrospectively analyzed the magnetic resonance (MR) images of 60 patients (26 males, 34 females, mean age 61 years) with branch-duct type and mixed-type IPMNs. The IPMNs were diagnosed clinically in 39 patients and histologically in 21 patients. The malignant potential was classified by MR imaging based on the international consensus guidelines for the management of IPMN established in 2017. Morphologically, 42 patients had "worrisome features" and three had "high-risk stigmata." Histologically, 14 lesions were diagnosed as low-grade dysplasia and seven as intermediate-grade dysplasia. The T1ϱ, T2, and ADC values of cyst fluid in each patient's largest cyst were measured on the same slice, avoiding solid components. Spearman's rank correlation test was used to determine the correlation between the morphological malignancy and the T1ϱ, T2, and ADC values. These values were also compared between the low-grade and intermediate-grade groups by Mann-Whitney U-test. RESULTS: There was a significant rank-correlation between the morphological classification and T2 value (p=0.04). The T2 value of the intermediate-grade group was significantly higher than that of the low-grade group (p=0.03). No significant correlations were morphologically or histologically obtained regarding T1ϱ and ADC. CONCLUSION: The T2 value of cyst fluid together with other MR-signs may be useful for predicting the malignant switch in IPMN of the pancreas.

Pancreatic hamartoma: detection of harbouring NAB2::STAT6 fusion gene.

Hamartomas in the pancreas are rare and are often histologically and morphologically similar to solitary fibrous tumours (SFTs). We examined the differences between hamartomas and SFTs at the molecular level. METHODS AND RESULTS: Thirteen patients histopathologically diagnosed with pancreatic hamartoma were included in the study. We also performed STAT6 immunohistochemistry (IHC), which is used in the diagnosis of SFT. Furthermore, for the three cases in which RNA was extracted, reverse transcription polymerase chain reaction to search for NAB2::STAT6 fusions was used. Macroscopically, 13 patients had well-demarcated tumour lesions. Histologically, no islets of Langerhans were observed in the lesions, acinar tissue and ducts were unevenly distributed and elastic fibres were not observed around the ducts by Elastica van Gieson staining. One case contained a lipomatous hamartoma composed mainly of adipose tissue. Seven of the 13 cases demonstrated expression of STAT6 in the nuclei of intervening spindle cells. NAB2::STAT6 fusions were observed in two of the three cases in which RNA was extracted. These two cases also demonstrated STAT6 expression in spindle cells using STAT6 IHC. In one case of lipomatous hamartoma, we did not confirm NAB2::STAT6 fusion or STAT6 expression in STAT6 IHC. CONCLUSION: Of the 13 patients histopathologically diagnosed with hamartoma, two demonstrated NAB2::STAT6 fusions, suggesting the existence of pancreatic hamartomas with molecular-level components identical to those of SFT.

RNF43 as a predictor of malignant transformation of pancreatic mucinous cystic neoplasm.

Mucinous cystic neoplasm (MCN) of the pancreas rarely progresses to invasive carcinoma, but few studies have analyzed genomic alterations involved in its malignant transformation. The relationships of ring finger protein 43 (RNF43) mutations with cytological atypia, RNF43 protein expression, and Wnt signaling proteins in MCN remain unclear. This study included 106 MCN cases, classified into 89 low-grade dysplasia (LG), 9 high-grade dysplasia (HG), and 8 invasive carcinoma (INV). We analyzed HG/INV and LG lesions of 9 HG/INV cases and LG lesions of 9 LG cases using targeted sequencing and confirmed the protein expression of RNF43 and ß-catenin. The frequency of RNF43 mutations was significantly higher in HG/INV cases than in LG cases. Furthermore, HG/INV lesions (56%) and LG lesions (33%) of HG/INV cases possessed RNF43 mutation, whereas no such mutation was detected in any LG cases. The expression of RNF43 was reduced in 71% of HG/INV cases and significantly correlated with histological grade and aberrant expression of ß-catenin. In 3 of 5 RNF43-mutated cases, the expression of RNF43 was reduced, but there was no significant correlation between RNF43 mutation and protein expression. MCNs frequently harbored KRAS mutations, at rates of 100% in HG/INV lesions and 50% in LG lesions of HG/INV and LG cases. There was no significant difference in mutation frequency in LG lesions between HG/INV and LG cases. These results suggest that RNF43 mutations may be involved in and predictive of malignant transformation from an early stage of MCN.

Histological background of dedifferentiated solitary fibrous tumour.

AIMS: Dedifferentiation is a histological phenomenon characterised by abrupt transition of histology to a sarcomatous component with high-grade malignant potential in solitary fibrous tumour (SFT). The authors histologically reviewed SFT cases to reveal the histological background of dedifferentiated SFTs. METHODS: Clinicopathological and histopathological findings of 145 SFT cases were reviewed. Immunohistochemical staining and genetic analysis were also performed. RESULTS: The non-dedifferentiated components showed a cellular component in 45 of 145 (31%), high mitotic rate (≥4/10 high-powered field) in 12 of 145 (8.2%) tumours, necrosis in 7 of 145 (4.8%) tumours, multinodular growth pattern in 39 of 132 (29.5%) available tumours and intratumoural fibrous septa in 37 of 131 (28.2%). Immunohistochemically, the non-dedifferentiated components were positive for CD34 in 128 of 141 (90.7%), bcl-2 in 101 of 133 (75.9%), nuclear pattern of ß-catenin in 64 of 127 (50.3%) and p16 in 22 of 140 (15.7%). Loss of Rb protein expression was detected in 17 of 110 (15.4%) cases. Statistically, cellular component, multinodular structure, p16 overexpression and Rb protein loss were significantly associated with dedifferentiation. Moreover, cellular component and multinodular structure were significantly associated with p16 overexpression and Rb protein loss. All the non-deddifferentiated components showed wild type of p53 expression. The dedifferentiated components of all 10 dedifferentiated tumours presented positivity for p16 in 9 of 10 (90%) and mutational type of p53 in 5 of 10 (50%). Loss of Rb protein expression was detected in 6 of 10 (60%). CONCLUSIONS: The authors propose that cellular or multinodular transformation may be associated with dedifferentiation. They also suggest that cellular and multinodular transformation may be associated with p16 overexpression and Rb downregulation.

Relationship between cellular morphology and abnormality of SWI/SNF complex subunits in pancreatic undifferentiated carcinoma.

PURPOSE: Pancreatic undifferentiated carcinoma (UDC) is a rare tumor with a worse prognosis than pancreatic ductal adenocarcinoma (PDAC). Recent study showed that UDC exhibits loss of SMARCB1, which is one of the subunits of the SWI/SNF complex. However, whether there are abnormalities of other SWI/SNF complex subunits in UDC has remained unknown. In this study, we attempted to clarify whether the loss of SWI/SNF complex subunits is related to the pathogenesis of UDC by comparing undifferentiated component (UC) and ductal adenocarcinoma component (DAC). METHODS: Genetic analysis of the ten UCs and six DACs was performed. The expression of ARID1A, SMARCA2, SMARCA4, SMARCB1, SMARCC1, and SMARCC2 in formalin-fixed, paraffin-embedded tumor tissues collected by surgical resection from 18 UDC patients was evaluated immunohistochemically. Moreover, two pancreatic cell lines were evaluated for the effects of siARID1A on the mRNA and protein expression of E-cadherin, vimentin, and epithelial-mesenchymal transition (EMT)-related markers by qRT-PCR, western blotting, and immunofluorescence staining. RESULTS: UCs tended to have a higher frequency of mutation in ARID1A, SMARCA4, and SMARCC2 than DACs. Immunohistochemically, UCs revealed reduced/lost expression of ARID1A (72%), SMARCB1 (44%), SMARCC1 (31%), and SMARCC2 (67%). Reduced/lost expression of ARID1A, SMARCB1, and SMARCC2 was significantly more frequently observed in UCs than in DACs. In the pancreatic cell lines, western blotting and qRT-PCR showed that the downregulation of ARID1A increased the expression of vimentin and EMT-related markers. CONCLUSION: Our results suggest that the abnormality of SWI/SNF complex subunits, especially ARID1A, is one of the factors behind the morphological change of UDC.

Pathological review of cardiac amyloidosis using autopsy cases in a single Japanese institution.

AIM: Amyloidosis is a systemic or localized disease of protein deposition characterized by amorphous eosinophilic morphology and positivity of Congo Red staining. The typing of amyloidosis is becoming increasingly important because therapeutic agents for each amyloidosis type have been developed. Herein, the authors review the autopsy cases at an institution to reveal the putative Japanese characteristics of each amyloidosis type and evaluate the clinicopathological significance of each type. MATERIALS AND METHODS: A total of 131 autopsy cases of systemic and localized amyloidosis were retrieved for classification by immunohistochemistry. Immunohistochemistry for transthyretin, amyloid A (AA), immunoglobulin light-chain kappa and lambda, and ß2-microglobulin was performed for all cases. RESULTS: The 131 amyloidosis cases were classified as follows: 71 cases (54.2%) of transthyretin amyloidosis, 32 cases (24.4%) of AA amyloidosis, 8 cases (6.1%) of light-chain amyloidosis, and 5 cases (3.8%) of ß2-microglobulin amyloidosis, along with 15 equivocal cases (11.5%). All cases showed myocardial involvement of amyloidosis. Histopathologically, the transthyretin type was significantly associated with the interstitial and nodular patterns, and with the absence of the perivascular and endocardial patterns. The AA type was significantly associated with the perivascular and endocardial patterns, and with the absence of the nodular pattern. CONCLUSION: The authors revealed the putative characteristics of cardiac amyloidosis in Japan by using autopsy cases. About 90% of amyloidosis cases were successfully classified using only commercially available antibodies.

Prognostic implications of the coexisting precursor lesion types in invasive gallbladder cancer.

Invasive gallbladder carcinoma (GBC) is preceded by two main types of precursor lesions: intracholecystic papillary-tubular neoplasms (ICPNs) and biliary intraepithelial neoplasias (BilINs). Invasive GBCs with an ICPN component have more favorable prognoses than those without an ICPN component. Some BilINs show a relatively exophytic papillary pattern but do not meet the ICPN criteria; at our institution, we call these papillary neoplasias. To clarify the clinical significance of papillary neoplasia, we herein examined 80 invasive GBCs and classified them into three groups based on the type of preinvasive lesions: those with ICPN (ICPN group, n = 35), those with papillary neoplasia (pap-neoplasia group, n = 13), and those without ICPN/papillary neoplasia (group without ICPN/pap-neoplasia, n = 32). We then compared the prognostic differences and characterized the tumors of each group by determining the immunohistochemical expressions of various biomarkers. The overall survival periods of the ICPN and pap-neoplasia groups were significantly longer than that of the group without ICPN/pap-neoplasia (P < 0.0001, P = 0.0036, respectively). Multivariate analysis revealed that lacking ICPN/papillary neoplasia was independently associated with poor prognosis (P = 0.0007), as were poor differentiation (P = 0.0395), presence of preoperative symptoms (P = 0.0488), and advanced stage (P = 0.0234). Invasive components of the ICPN and pap-neoplasia groups were characterized by higher expressions of p16 and p53 compared with those of the group without ICPN/pap-neoplasia. The prognoses of the invasive GBCs with either papillary neoplasia or ICPN were thus more favorable than those of the invasive GBCs without ICPN/pap-neoplasia. Invasive GBCs with exophytic papillary preinvasive lesions (ICPN and papillary neoplasia) may be biologically different from those without such lesions.

A deep learning model to detect pancreatic ductal adenocarcinoma on endoscopic ultrasound-guided fine-needle biopsy.

Histopathological diagnosis of pancreatic ductal adenocarcinoma (PDAC) on endoscopic ultrasonography-guided fine-needle biopsy (EUS-FNB) specimens has become the mainstay of preoperative pathological diagnosis. However, on EUS-FNB specimens, accurate histopathological evaluation is difficult due to low specimen volume with isolated cancer cells and high contamination of blood, inflammatory and digestive tract cells. In this study, we performed annotations for training sets by expert pancreatic pathologists and trained a deep learning model to assess PDAC on EUS-FNB of the pancreas in histopathological whole-slide images. We obtained a high receiver operator curve area under the curve of 0.984, accuracy of 0.9417, sensitivity of 0.9302 and specificity of 0.9706. Our model was able to accurately detect difficult cases of isolated and low volume cancer cells. If adopted as a supportive system in routine diagnosis of pancreatic EUS-FNB specimens, our model has the potential to aid pathologists diagnose difficult cases.

Collision of a pancreatic ductal adenocarcinoma and a pancreatic neuroendocrine tumor associated with multiple endocrine neoplasm type 1.

A 54-year-old man with pancreatic head tumor had undergone pancreaticoduodenectomy and was diagnosed with pancreatic neuroendocrine tumor (P-NET) associated with sporadic multiple endocrine neoplasm type 1. Five years after the resection, P-NET recurred and liver metastases were observed. He was treated with a somatostatin analog. Eleven years after the resection, computed tomography revealed a new pancreatic hypodense and hypovascular mass adjacent to the P-NET that was diagnosed as pancreatic adenocarcinoma via endoscopic ultrasound-guided fine-needle aspiration. He underwent a total remnant pancreatectomy. Pathological examination showed that the lesion was constituted by a pancreatic ductal adenocarcinoma (PDAC) and a neuroendocrine tumor. Additionally, the invasive ductal carcinoma collided with the neuroendocrine tumor. Both PDAC and P-NET cells were observed in the collision area. We could observe the onset of PDAC during the treatment of P-NET. Moreover, we are the first to report the case of a collision of pancreatic endocrine and exocrine tumors diagnosed preoperatively.

A rare case of PSA-negative metastasized prostate cancer to the stomach with serum CEA and CA19-9 elevation: a case report.

BACKGROUND: Metastatic cancer to the stomach is relatively rare. Prostate-specific antigen (PSA) is a reliable biomarker used in the screening and management of patients with prostate cancer. However, it is difficult to definitively diagnose a PSA-negative metastatic gastric tumor of prostate cancer because the cancer sometimes resembles primary gastric cancer in clinical images. It is also difficult to distinguish metastatic cancer from primary cancer even in the pathological examination of biopsy samples when the lesion is poorly differentiated adenocarcinoma. There is a possibility that the characteristics of the cancer are changed during treatment such as chemotherapy or radiation therapy. Therefore, careful consideration is required for surgical indication. CASE PRESENTATION: A 60-year-old male underwent radical prostatectomy and subsequent radiation therapy for advanced prostate cancer (pT3N1M0) 10 years previously, and hormone therapy was started for metachronous multiple bone metastasis 10 months before. Upper gastrointestinal endoscopy revealed an irregular depressed lesion with a convergence of folds at the greater curvature of the upper gastric body. Biopsy showed poorly differentiated adenocarcinoma that was negative for PSA upon immunohistochemistry. He had high serum carcinoembryonic antigen (CEA) (946.1 ng/ml) and carbohydrate antigen 19-9 (CA19-9) (465.1 U/ml) levels with no elevation of PSA (0.152 ng/ml). The tumor was diagnosed as primary gastric cancer based on the clinical imaging and pathological examination of the biopsy sample including the PSA staining. Based on the diagnosis, laparoscopic proximal gastrectomy with lymphadenectomy was performed. However, pathological examination of the resected specimen revealed poorly differentiated adenocarcinoma that was positive for other prostate markers such as androgen receptor. Thus, the patient was diagnosed with metastasized prostate cancer to the stomach. CONCLUSIONS: We report a case of metastatic gastric cancer of prostate cancer 10 years after radical prostatectomy. In the present case, it was difficult to diagnose a metastatic gastric tumor of prostate cancer preoperatively, because of its resemblance to primary gastric cancer without PSA expression and no serum PSA elevation. Although a rare case entity, it is important to consider the possibility of a metastatic gastric tumor when the surgical indication is determined in cases with another co-existing cancer.

Chronic inflammatory changes and oxidative stress in the background of "pancreatic ductal adenocarcinoma concomitant with intraductal papillary mucinous neoplasm".

Cases of "pancreatic ductal adenocarcinoma (PDAC) concomitant with intraductal papillary mucinous neoplasm" (IPMN) have multiple PDAC lesions more frequently than cases of "PDAC without IPMN". However, the mechanism of carcinogenesis in this former disease category remains unknown. The main objective of this work was thus to investigate the effects of chronic inflammation on carcinogenesis in PDAC cases. We selected 31 "PDAC concomitant with IPMN" patients and 58 "PDAC without IPMN" patients and pathologically evaluated their background pancreatic parenchyma. Fibrosis and inflammation scores of background pancreas were higher in "PDAC concomitant with IPMN" than in "PDAC without IPMN" (P < 0.0001 and P < 0.0001, respectively), whereas the fatty infiltration score of background pancreas was high in "PDAC without IPMN" (P = 0.0024). Immunohistochemically, the expression of 8-hydroxy-2'-deoxyguanosine (8-OHDG), an oxidative stress marker, in the background pancreas was high in "PDAC concomitant with IPMN" compared with that in "PDAC without IPMN" (P < 0.0001). Chronic inflammation activates oxidative stress in tissue throughout the pancreas and probably confers susceptibility to tumorigenesis in "PDAC concomitant with IPMN".

Natural history and clinical outcomes of pancreatic neuroendocrine neoplasms based on the WHO 2017 classification; a single-center experience of 30 years.

BACKGROUND/OBJECTIVES: This single-center study aimed to evaluate treatment outcomes and long-term prognosis of patients with pancreatic neuroendocrine neoplasms (PanNENs) based on the World Health Organization (WHO) 2017 classification. METHODS: We enrolled 245 patients with PanNENs treated at Kyushu University Hospital between January 1987 and March 2018. PanNENs were categorized according to the WHO 2017 classification or further subdivisions of Ki-67 index. Clinicopathological features, median survival time (MST), and prognostic factors were retrospectively analyzed. RESULTS: The number of PanNENs, especially non-functioning PanNENs, has increased over the last decade. The mean MST of all patients was 202 months; which was longest in patients with NET G1 (n = 145, MST = 261 months) relative to NET G2 (n = 72, 132 months), NET G3 (n = 3, 34 months) and NEC G3 (n = 17, 9 months). Prognosis in patients with surgery as the first-line treatment was significantly better than in those with drug therapy. However, 26% of patients who underwent curative resection developed recurrence after a median time of 28.7 months. In unresectable PanNENs (n = 97), the MST and 5-year survival rate were 78 months and 55.8%, respectively. Poor differentiation, Ki-67 index of >10% and presence of liver metastasis were significant unfavorable predictors. Response to first-line therapy (stable disease/partial response) and three or more treatment regimens were significant favorable predictors for unresectable PanNENs according to multivariate analyses (p < 0.01). CONCLUSIONS: We demonstrated the utility of the WHO 2017 classification for PanNENs in the real clinical setting. For better prognosis in PanNENs, the use of three or more regimens should be considered.

Solid-type poorly differentiated adenocarcinoma of the stomach: Deficiency of mismatch repair and SWI/SNF complex.

ARID1A, one of the subunits in SWI/SNF chromatin remodeling complex, is frequently mutated in gastric cancers with microsatellite instability (MSI). The most frequent MSI in solid-type poorly differentiated adenocarcinoma (PDA) has been reported, but the SWI/SNF complex status in solid-type PDA is still largely unknown. We retrospectively analyzed 54 cases of solid-type PDA for the expressions of mismatch repair (MMR) proteins (MLH1, PMS2, MSH2, and MSH6), SWI/SNF complex subunits (ARID1A, INI1, BRG1, BRM, BAF155, and BAF170) and EBER, and mutations in KRAS and BRAF. We analyzed 40 cases of another histological type of gastric cancer as a control group. The solid-type PDAs showed coexisting glandular components (76%), MMR deficiency (39%), and complete/partial loss of ARID1A (31%/7%), INI1 (4%/4%), BRG1 (48%/30%), BRM (33%/33%), BAF155 (13%/41%), and BAF170 (6%/2%), EBER positivity (4%), KRAS mutation (2%), and BRAF mutation (2%). Compared to the control group, MMR deficiency and losses of ARID1A, BRG1, BRM, and BAF155 were significantly frequent in solid-type PDAs. Mismatch repair deficiency was associated with the losses of ARID1A, BRG1, and BAF155 in solid-type PDAs. In the MMR-deficient group, solid components showed significantly more frequent losses of ARID1A, BRG1, BRM, and BAF155 compared to glandular components (P = .0268, P = .0181, P = .0224, and P = .0071, respectively). In the MMR-proficient group, solid components showed significantly more frequent loss of BRG1 compared to glandular components (P = .012). In conclusion, solid-type PDAs showed frequent losses of MMR proteins and the SWI/SNF complex. We suggest that loss of the SWI/SNF complex could induce a morphological shift from differentiated-type adenocarcinoma to solid-type PDA.

Clinicopathological review of solitary fibrous tumors: dedifferentiation is a major cause of patient death.

Solitary fibrous tumor (SFT) is a soft-tissue neoplasm of intermediate malignant potential, presenting a wide histopathological spectrum. Poorer prognosis of hemangiopericytoma of the central nervous system (CNS), hypoglycemic SFT, and dedifferentiation are well-known characters of SFT, but their clinical significance were not demonstrated enough by large-sized study. Here, the clinicopathological features of SFTs are reviewed and the relationship between genetics and clinicopathological features is examined using 145 SFT cases. All cases were STAT6 IHC-positive and/or NAB2-STAT6 fusion gene-positive. Tumor location was classified into three categories: 30 pleuropulmonary, 96 non-pleuropulmonary/non-central nervous system (CNS), and 18 CNS tumors. The tumor developed recurrence in 21 of 93 available cases (22.5%), metastasis in 11 of 93 (11.8%), and tumor death in 9 of 93 (9.6%). Hypoglycemia occurred in 2 primary tumors and 1 metastatic tumor among 63 reviewable cases, and dedifferentiation occurred in 10 cases (6.8%) including 6 primary tumors, 2 recurrent tumors, and 2 metastatic tumors. Recurrence was positively associated with CNS location (p = 0.0109) and hypoglycemia (p = 0.001); metastasis was positively associated with CNS location (p = 0.0231), hypoglycemia (p < 0.0001), and dedifferentiation (p < 0.0001), while metastasis was negatively correlated with pleural location (p = 0.0471). Tumor death was positively associated with male sex (p = 0.0154), larger size (p = 0.0455), hypoglycemia (p < 0.0001), and dedifferentiation (p < 0.0001). Multivariate analysis revealed independent statistical significance of dedifferentiation for overall survival (p = 0.0467). Exon variant of the fusion gene had no statistical correlation with clinical outcome. In conclusion, dedifferentiation is a major prognostic factor of SFT, and specific location such as cerebromeningeal and intra-abdominal site and hypoglycemia also had a high risk for unfavorable prognosis.