Low-grade Appendiceal Mucinous Neoplasm with Appendiceal Reduction and Re-expansion Over a Two-year Period: A Case Report.

A 71-year-old woman was found to have submucosal tumor-like lesion on colonoscopy (CS) before gastric surgery, and computed tomography (CT) showed a 12-mm structure at the base of the appendix. The lesion could not be clearly detected on CT nine months later, but it had enlarged again on CT one year later; therefore, CS and endoscopic ultrasound (EUS) were performed. The lesion was determined to be cystic with viscous contents, and laparoscopic appendicectomy was performed. This is the first report of low-grade appendiceal mucinous neoplasm (LAMN) diagnosed by a histopathologic examination of a resected specimen showing shrinkage and re-expansion of the appendix.

BRCA1/2 reversion mutations in a pan-cancer cohort.

Tumor sensitivity to platinum (Pt)-based chemotherapy and poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors is increased by homologous recombination deficiency-causing mutations; in particular, reversion mutations cause drug resistance by restoring protein function. Treatment response is predicted by breast cancer susceptibility gene 1/2 (BRCA1/2) mutations; however, BRCA1/2 reversion mutations have not been comprehensively studied in pan-cancer cohorts. We aimed to characterize BRCA1/2 reversion mutations in a large pan-cancer cohort of Japanese patients by retrospectively analyzing sequencing data for BRCA1/2 pathogenic/likely pathogenic mutations in 3738 patients with 32 cancer types. We identified somatic mutations in tumors or circulating cell-free DNA that could restore the ORF of adverse alleles, including reversion mutations. We identified 12 (0.32%) patients with somatic BRCA1 (n = 3) and BRCA2 (n = 9) reversion mutations in breast (n = 4), ovarian/fallopian tube/peritoneal (n = 4), pancreatic (n = 2), prostate (n = 1), and gallbladder (n = 1) cancers. We identified 21 reversion events-BRCA1 (n = 3), BRCA2 (n = 18)-including eight pure deletions, one single-nucleotide variant, six multinucleotide variants, and six deletion-insertions. Seven (33.3%) reversion deletions showed a microhomology length greater than 1 bp, suggesting microhomology-mediated end-join repair. Disease course data were obtained for all patients with reversion events: four patients acquired mutations after PARP-inhibitor treatment failure, two showed somatic reversion mutations after disease progression, following Pt-based treatment, five showed mutations after both treatments, one patient with pancreatic cancer and BRCA1 reversion mutations had no history of either treatment. Although reversion mutations commonly occur in BRCA-associated cancers, our findings suggest that reversion mutations due to Pt-chemotherapy might be correlated with BRCA1/2-mediated tumorigenesis even in non-BRCA-associated histologies.

A case of breast cancer with extensive colon metastasis.

Breast cancer is one of the most common malignancies in women worldwide. Although most breast cancers are curable, in cases of metastasis, many are often found in the lungs, bones, liver, and central nervous system; however, metastasis to the gastrointestinal tract is rare. Invasive lobular carcinoma, which represents only 5%-10% of breast cancers, has a higher risk of metastasis to the gastrointestinal tract than invasive ductal carcinoma. Here, we report a rare case of gastrointestinal metastasis of invasive lobular carcinoma that spread extensively to the colonic mucosa. Given the improved survival rates of breast cancer patients with current treatments, many rarer metastatic diseases, including gastrointestinal metastases, are likely to be increased in the future.

miR-4653-3p overexpression is associated with a poor prognosis of pancreatic ductal adenocarcinoma via HIPK2 downregulation.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignant tumor. Several upregulated and downregulated microRNAs (miRNAs) are associated with invasiveness, tumorigenesis, and prognosis of PDAC. Herein, using in situ hybridization, we evaluated miR-4653-3p expression and pancreatic intraepithelial neoplasia (PanIN) and the association between miR-4653-3p expression and clinicopathological factors in PDAC patients. The miR-4653-3p target was also identified. Ninety PDAC cases, including 30 each with normal pancreatic ducts, low-grade PanINs, and high-grade PanINs, were evaluated. miR-4653-3p expression increased in the order-normal pancreatic duct, low-grade PanIN, high-grade PanIN, and PDAC-with no expression detected in normal pancreatic duct. High expression significantly correlated with advanced pathological T stage, lymph node metastasis, advanced Union for International Cancer Control stage, perineural invasion, venous involvement, and shorter overall and disease-specific survival. Homeodomain Interacting Protein Kinase 2 (HIPK2) was identified as a miR-4653-3p target based on mRNA microarray analysis and database screening. In MIA PaCa-2 cells, miR-4653-3p significantly downregulated HIPK2 expression. HIPK2 expression, unlike that of miR-4653-3p, decreased in the order-normal pancreatic duct, low-grade PanIN, high-grade PanIN, and PDAC. Low HIPK2 expression was associated with shorter overall and disease-specific survival in PDAC patients. Thus, miR-4653-3p associates with tumorigenesis and worse prognosis, partly by reducing HIPK2 expression.

Efficacy and Safety of Endoscopic Removal for Asymptomatic Common Bile Duct Stones in Comparison with Symptomatic Stones.

OBJECTIVE: Endoscopic removal is recommended for common bile duct stones (CBDs). However, in patients with asymptomatic CBDs, follow-up without treatment may be recommended because of the increased complication risks associated with asymptomatic CBDs removal. The objective of our study was to investigate the efficacy and safety of CBDs removal in asymptomatic patients. METHODS: Consecutive patients with naive papilla who underwent endoscopic retrograde cholangiopancreatography (ERCP) for the treatment of CBDs from April 2016 to August 2020 were retrospectively analyzed. We compared the efficacy and safety of CBDs removal in asymptomatic and symptomatic patients. RESULTS: We enrolled 300 patients, 53 asymptomatic and 247 symptomatic patients. Endoscopic CBDs removal was successful in all patients, except one symptomatic patient. However, the complete stone removal rate in a single session was significantly higher in the asymptomatic group than that in the symptomatic group. ERCP-related complications did not differ between the asymptomatic and symptomatic patients. The incidence of post-ERCP pancreatitis was similar and liver cirrhosis was the only significant risk factor for pancreatitis. CONCLUSION: Complication risks associated with endoscopic CBDs removal was not significantly different between asymptomatic and symptomatic patients. Liver cirrhosis was a significant risk factor of ERCP-related pancreatitis.

Analysis of Comorbidity for Patients with Pancreatic Cysts in Medical Checkup Screening.

OBJECTIVES: We investigated whether there is a difference in the frequency of comorbidity between patients with pancreatic cysts and those without pancreatic cysts by abdominal ultrasonography in patients undergoing medical checkup screening. METHODS: The subjects were 6,627 patients who underwent abdominal ultrasonography at Tokai University Hachioji Hospital's Health Screening Center between April 2019 and March 2020. RESULTS: Of the total 6,627 patients, 158 (2.4%) were pointed out to have pancreatic cysts. Multivariate analysis revealed that the related factors were female sex, age 60 years or older, diabetes, lung cancer, and uterine/ovarian cancer. CONCLUSION: Unlike pancreatic cancer, pancreatic cysts are more common in women. In addition, it is known that pancreatic cysts have a high complication rate of cancers of other organs; lung cancer and uterine/ovarian cancer were identified as high-risk factors in this study.

[A case of simultaneous multicentric cancer in the gallbladder duct and the common bile duct without pancreaticobiliary maljunction].

A 68-year-old man who underwent cholecystectomy for acute cholecystitis and was diagnosed with gallbladder duct carcinoma was referred to our hospital. Postoperative computed tomography showed thickening of the middle to lower bile duct without any tumorous lesions. Endoscopic retrograde cholangiopancreatography and intraductal ultrasonography revealed irregular wall thickening of the lower bile duct and apparent infiltration of gallbladder duct tumor to the common bile duct without pancreaticobiliary maljunction. Subtotal stomach-preserving pancreaticoduodenectomy was performed. Pathological examination showed papillary adenocarcinoma and tubular adenocarcinoma in the gallbladder duct and BilIN-3 lesion in the distal bile duct. The final diagnosis was biliary simultaneous multicentric cancer without pancreaticobiliary maljunction.

Low expression of DDX5 is associated with poor prognosis in patients with pancreatic ductal adenocarcinoma.

AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies. Hence, there is a need for new markers and treatment strategies. P68/DEAD box protein 5 (DDX5) is an ATP-dependent RNA helicase of the DEAD box protein family. It is a prognostic marker for several cancers. In this study, we aimed to evaluate the expression and clinical relevance of DDX5 in PDAC. METHODS: DDX5 expression in tissue microarray blocks containing 230 PDAC samples was examined using immunohistochemical analysis. DDX5 expression was considered high when more than 50% of the cells were stained and low when less than 50% of the cells were stained. We investigated the association between DDX5 expression and clinicopathological parameters, including patient survival. RESULTS: The nuclei of normal pancreatic ducts, normal acinar cells and PDAC cells were stained positive for DDX5 although the intensity and distribution of DDX5 expression varied. Islet cells showed strong and diffuse staining of DDX5. DDX5 expression was low and high in 148 (64.3%) and 82 cases (35.7%), respectively. Low DDX5 expression was significantly associated with an advanced pT factor (pT2-pT3: tumour size,>20 mm), lymphatic involvement, advanced tumour-node-metastasis (TNM) stage (stages IIB, III, and IV), and venous involvement. In addition, the multivariate analysis revealed that DDX5 expression is an independent prognostic factor for PDAC. CONCLUSION: These results suggest that DDX5 plays an important role in tumour invasiveness and PDAC prognosis.

Objective assessment of tumor regression in post-neoadjuvant therapy resections for pancreatic ductal adenocarcinoma: comparison of multiple tumor regression grading systems.

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.

Hyalinized stroma is a characteristic feature of pancreatic intraductal oncocytic papillary neoplasm: An immunohistochemical study.

Hyalinized stroma (HS) is a dense, eosinophilic, and amorphous extracellular material in the stroma. HS is observed in several tumors; however, it has not been comprehensively studied in pancreatic intraductal papillary mucinous neoplasm (IPMN) or intraductal oncocytic papillary neoplasm (IOPN). Here, we aimed to evaluate the immunohistochemical and microscopic characteristics of HS in IPMN and IOPN. The prevalence of HS was determined in 168 cases of IPMN, including intestinal type (IPMN-I), gastric type (IPMN-G), and pancreatobiliary type (IPMN-PB), as well as in 11 cases of IOPN. Immunohistochemical staining for laminin and collagen (types I, II, III, IV, and V), as well as Congo red staining were performed in IPMN and IOPN cases containing HS. The prevalence of HS among the IPMN and IOPN specimens was 1.2% (2/168 cases) and 45.5% (5/11 cases), respectively. The prevalence rates of HS in each IPMN subtype were as follows: 2.2% (2/91 cases) in IPMN-G, and 0% in IPMN-PB and IPMN-I. All seven HS cases were positive for collagen I, III, IV, and V but were negative for Congo red staining. Most cases showed negative, focal, or weak expression of laminin and type II collagen. These findings indicate that HS is associated with IOPN and is primarily composed of collagen fibers.

Cancer-associated fibroblasts are a useful cytological finding for diagnosing pancreatic ductal adenocarcinoma.

INTRODUCTION: Cancer-associated fibroblasts (CAFs) are activated fibroblasts or myofibroblasts that play a crucial role in the invasiveness of pancreatic ductal adenocarcinoma (PDAC). In this study, the cytological features and diagnostic significance of CAFs based on pancreatic duct brushing cytology (PDBC) were evaluated. METHODS: The prevalence of fibrous stroma (FS) including CAFs on PDBC in 42 PDAC cases and 33 benign cases was retrospectively investigated. The average nuclear size of fibroblasts was compared between PDAC and benign cases to distinguish CAFs from normal FS. RESULTS: Overall, FS was observed in 25 PDAC cases (60%) and eight benign cases (24%). The average nuclear size of FS in PDAC cases was significantly larger than that in benign cases. From the receiver operating characteristics analysis, the cut-off value of the nuclear size of FS for the diagnosis of PDAC was defined as 10.22 µm. FS with nuclei over 10.22 µm in size in PDAC cases had clear prominent nucleoli. In contrast, FS in benign cases had no clear nucleoli. Thus, CAFs on PDBC were considered to be FS with nuclei over 10.22 µm in size and prominent nucleoli. The presence of CAFs on PDBC had 100% positive predictive value and specificity for the diagnosis of PDAC. CONCLUSIONS: This study suggested that CAFs on PDBC could be distinguished from normal FS by large nuclear size (over 10.22 µm) and prominent nucleoli and that CAFs on PDBC may be used for the diagnosis of PDAC.

A Case of Endoscopic Mucosal Resection of Carcinoma in Adenoma at the Minor Duodenal Papilla.

Here, we describe a case of minor papillary adenocarcinoma in adenoma that was treated with endoscopic mucosal resection (EMR). In a 67-year-old woman, sigmoid colon cancer was incidentally detected on preoperative upper gastrointestinal endoscopy. Endoscopy revealed a slightly elevated lesion at the minor duodenal papilla. The findings of a histopathologic examination were suggestive of adenocarcinoma. Computed tomography and magnetic resonance images identified a minute tumor, whereas endoscopic ultrasonography revealed that the tumor did not spread to the pancreas. We performed EMR of this lesion. There were no complications, and relapse has not occurred in 3 years. Cases of minor papillary adenocarcinoma treated with EMR are quite rare.

Histological and immunohistochemical analyses of splenic epidermoid cysts.

Splenic epidermoid cyst (SEC) is a rare condition. We aimed to evaluate the immunohistochemical profiles of the epithelial lining of SECs. A total of 7 SEC cases were analyzed: 2 cases involved a monolayered epithelial lining and 5 cases involved a multilayered epithelial lining. Among the multilayered SECs, the superficial/luminal layer showed mucin 4 (MUC4), cytokeratin 5/6 (CK5/6), and CK7 expression in 5 cases (100%); MUC1, carcinoembryonic antigen (CEA), CA19-9, and thrombomodulin expression in 4 cases (80%); Wilms' tumor-1 (WT-1) and Hector Battifora mesothelial-1 (HBME-1) expression in 2 cases (40%), but it did not express p63 or D2-40. The basal layer expressed MUC1, CK5/6, p63, and thrombomodulin in 5 cases (100%); CK7 and WT-1 in 4 cases (80%); D2-40 in 3 cases (60%); CA19-9 and HBME-1 in 2 cases (40%) and MUC4 in 1 case (20%) but it did not express CEA. The analysis showed that all cases of multilayered SECs were negative for MUC2, MUC5AC, MUC6, CK20, calretinin, uroplakin-II, and uroplakin-III. Both cases of monolayered SECs expressed CK5/6, CK7, HBME-1, WT-1, and thrombomodulin but not MUC2, MUC4, MUC5AC, MUC6, p63, CEA, CK20, CA19-9, D2-40, uroplakin-II, or uroplakin-III. One case of monolayered SEC expressed MUC1 and calretinin. Our findings indicate that monolayered SECs have mesothelial-like characteristics, whereas multilayered SECs have glandular and squamous-like characteristics besides mesothelial-like characteristics. Furthermore, monolayered SECs may develop from mesothelial inclusion and monolayered SECs develop squamous and glandular metaplasia, which results in multilayered SECs.

Successful Endoscopic Removal of a Biliary Stent with Stent-Stone Complex after Long-Term Migration.

A 49-year-old man was referred to our hospital for an abnormality of the hepatobiliary enzyme. The patient was diagnosed with primary sclerosing cholangitis 9 years ago, and he had a biliary stent with a string placed as an inside stent. We attempted to remove the stent 6 months later, but the string was cut off, so the stent could not be removed. Removal was attempted again, but the patient cancelled the outpatient appointments. During the examination performed at the present visit, we discovered that the biliary stent had migrated into the bile duct, and a stone had formed around the stent. We attempted to remove the stent-stone complex by endoscopic retrograde cholangiopancreatography, but it was difficult; thus, we decided to implant a new biliary stent and remove the other stent later. When we performed endoscopic retrograde cholangiopancreatography again 2 days later, the bile duct axis was linearized thanks to the additional stent, enabling us to grab the migrated stent with stent-stone complex using grasping forceps and to successfully pull it out. By implanting an additional plastic stent temporarily, we were able to straighten the biliary axis and endoscopically remove the biliary stent that migrated and caused the development of stent-stone complex in a 2-staged approach.

Comparison between Endoscopic Treatment and Surgical Drainage of the Pancreatic Duct in Chronic Pancreatitis.

BACKGROUND: Treatment of recurrent chronic obstructive pancreatitis is pancreatic duct decompression with endoscopic drainage (endoscopic pancreatic stenting [EPS] with extracorporeal shockwave lithotripsy [ESWL]) or surgical drainage. Despite the recent popularization of endoscopic drainage, treatment or stent removal is difficult in many patients. We compared the efficacy, safety, and medical cost of endoscopic and surgical treatments. PATIENTS AND METHODS: We retrospectively compared the treatment course and medical cost of hospitalization between 41 patients who had undergone pancreatic stenting between 2006 and 2010 (EPS group) and 10 patients who had undergone surgery for poor control of pancreatitis between 2001 and 2005 (surgical drainage group). RESULTS: No intergroup differences were observed in causes, symptoms, disease duration, smoking history, or endocrine and exocrine functions. The technical success rate was 100% in both groups, and pain had improved in all of the patients in both groups. The incidences of complications did not differ significantly, and the mortality rate was 0% in both groups. The rehospitalization rate was significantly higher in the EPS group (78%) than that in the surgical drainage group (20%; P<0.01). This was considered attributable to rehospitalization for stent replacement. The effects to improve endocrine and exocrine functions were not different between the two groups before and after treatment, and the current condition was maintained in 80% or more of the patients. For the entire EPS group, the mean hospitalization period was 18 days and the mean medical cost of hospitalization was 2,133,330 yen. For the entire surgical drainage group, the mean hospitalization period was 23 days and the mean medical cost of hospitalization was 2,246,548 yen, thus indicating no significant differences between the two groups. CONCLUSIONS: Although both endoscopic and surgical treatments achieved high symptom control and safety rates, re-hospitalization is required for stent replacement, which leads to poor cost-effectiveness, particularly in patients in whom stent removal is difficult. Endoscopic treatment for severe pancreatic duct stenosis will need to be advanced and evaluated in the future.

Nectin-1 expression in cancer-associated fibroblasts is a predictor of poor prognosis for pancreatic ductal adenocarcinoma.

PURPOSE: Nectin-1 is a cell adhesion molecule that regulates the formation of adherens junctions and tight junctions. We measured the expression of nectin-1 in cancer-associated fibroblasts (CAFs) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: Nectin-1 expression was measured via immunohistochemistry using tissue microarray blocks constructed from resected PDAC tissue from 258 patients. We screened for associations between nectin-1 expression and clinicopathological parameters. According to the percentage of CAFs stained, expression was classified as negative at ≤ 30% and positive at > 30%. RESULTS: Nectin-1 expression was confirmed in CAFs from 64 patients (24.8%), and was associated with lymph node metastasis (p = 0.016), advanced Union for International Cancer Control stage (p = 0.016), perineural invasion (p = 0.022), pancreatic head tumors (p = 0.023), and shorter overall survival (p = 0.003). Multivariate analysis revealed that nectin-1 expression in CAFs was an independent prognostic factor (p = 0.038). CONCLUSIONS: Diffuse nectin-1 expression in the CAFs of PDAC patients is associated with invasion, metastasis, and shorter survival.

A Case of Pedunculated Esophageal Leiomyoma Successfully Treated by Endoscopic Mucosal Resection.

Leiomyoma is one of the most commonly observed esophageal submucosal tumors, often appearing as a smooth-surfaced and semicircular protruded lesion. It sometimes grows toward the esophageal lumen and may be pedunculated in rare cases. We encountered a case of a pedunculated esophageal submucosal tumor diagnosed before treatment as a leiomyoma originating in the muscularis mucosae of a 68-year-old man. As the tumor arose in the muscularis mucosae, it could be safely resected via an endoscopic procedure. Only one case of pedunculated leiomyoma has been reported to date, and we herein report the second case, which was successfully treated by a minimally invasive endoscopic technique.

An Intra-Abdominal Desmoid Tumor, Embedded in the Pancreas, Preoperatively Diagnosed as an Extragastric Growing Gastrointestinal Stromal Tumor.

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.

Epidermoid cysts are a characteristic feature of intrapancreatic but not of extrapancreatic accessory spleens.

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.

A Serous Cystic Neoplasm of the Pancreas Coexisting with High-Grade Pancreatic Intraepithelial Neoplasia Mimicking an Intraepithelial Papillary Mucinous Neoplasm: A Case Report.

Serous cystic neoplasms of the pancreas are rare exocrine pancreatic neoplasms, most of which are benign and do not communicate with the pancreatic duct. Pancreatic intraepithelial neoplasm (PanIN) is considered a precursor of ductal adenocarcinoma that is microscopically recognized in pancreatic ducts. A 67-year-old Japanese woman presented with a 10-mm multilocular cystic lesion at the pancreatic body. Magnetic resonance pancreatography showed stenosis of the main pancreatic duct at the pancreatic body and dilatation of the distal side of the main pancreatic duct. Furthermore, communication between the cystic lesion and the main pancreatic duct was suspected based on magnetic resonance pancreatography findings. Distal pancreatectomy was performed under the preoperative diagnosis of intraductal papillary mucinous neoplasm. Histologically, the cystic lesion was lined with a non-atypical cuboidal or flat epithelium with clear cytoplasm and was thus diagnosed as a serous cystic neoplasm. High-grade PanIN lesions with stromal fibrosis were observed at the main and branch pancreatic ducts. Histological examination revealed no communication between the serous cystic neoplasm and the pancreatic ducts. Immunohistochemically, the epithelium of the serous cystic neoplasm showed positive anti-von Hippel-Lindau antibody staining, whereas the epithelium of the PanIN showed negative staining. A serous cystic neoplasm coexisting with another pancreatic neoplasm is rare. When dilatation of the main or branch pancreatic ducts coexists with a serous cystic neoplasm, as in this case, the lesion clinically mimics an intraductal papillary mucinous neoplasm.