Rethinking fibrinogen storage disease of the liver: ground glass and globular inclusions do not represent a congenital metabolic disorder but acquired collective retention of proteins.

Three types of intracytoplasmic inclusions immunoreactive to fibrinogen are collectively diagnosed as hepatic fibrinogen storage disease. This study aimed to better characterize ground glass (type II) and globular (type III) fibrinogen inclusions by the pathological examination of 3 cases and a literature review. Three adults (age: 32-64 years; male/female = 2:1) were unexpectedly found to have fibrinogen-positive ground glass changes (type II inclusions) by liver needle biopsy, against a background of acute hepatitis E, resolving acute cholangitis, or severe lobular hepatitis of unknown etiology. One patient also had fibrinogen-positive intracytoplasmic globules (type III inclusions) in the first biopsy, but they were not present in a second biopsy. None had coagulation abnormalities or hypofibrinogenemia. On immunostaining, both inclusions were strongly positive for not only fibrinogen but also C-reactive protein and C4d. Ultrastructurally, ground glass changes corresponded to membrane-bound cytoplasmic inclusions containing amorphous, granular material. The pathological features of type II fibrinogen inclusions were identical to those of pale bodies in hepatocellular carcinoma. The literature review suggested that type I fibrinogen inclusions characterized by a polygonal appearance are strongly associated with mutations in fibrinogen genes, coagulopathy, and family history, whereas type II/III inclusions are immunoreactive to multiple proteins and typically develop in cases of other unrelated liver diseases. In conclusion, type II and III fibrinogen inclusions do not represent a true hereditary storage disease but instead the collective retention of multiple proteins. Given the lack of clinical significance, a less specific name (e.g., pale body) may be more appropriate for those inclusions.

[A Case of Granulocyte-Colony Stimulating Factor Producing Breast Cancer That Caused Rapid Progression].

We report a case of granulocyte-colony stimulating factor(G-CSF)producing breast cancer in a 54-year-old woman. Eight months after surgery, multiple liver and pulmonary metastases appeared. They progressed rapidly in 2 weeks and she had a high fever of 38 degrees. Serum G-CSF was high, and positive cells were found by immunostaining of the primary tumor. Chemotherapy was initially successful but she died 4 months after relapse.

Hepatic angiomyolipomas may overexpress TFE3, but have no relevant genetic alterations.

The fusion or amplification of TFE3 has been identified as one of the molecular events underlying tumorigenesis in perivascular epithelioid cell tumors (PEComas). TFE3 rearrangements in PEComas are related to the morphological features of the epithelioid appearance and weaker expression of immunohistochemical muscular markers. This study aimed to clarify whether these genetic alterations are involved in hepatic angiomyolipomas (AMLs), which are a member of the PEComa tumor family. We examined 28 liver specimens (15 biopsies and 13 surgical specimens) of hepatic AMLs obtained from 26 patients. Renal AMLs (n=20), extrahepatorenal PEComas (n=3), lymphangiomyomatosis (n=8), and hepatocellular carcinomas (n=40) were used as a control. A histologic comparison between hepatic and renal AMLs revealed that the epithelioid appearance was more common in hepatic tumors (38% versus 0%, P=.006). In immunohistochemistry, the expression of HMB45 and Melan-A appeared to be more widespread in hepatic AMLs than in renal AMLs, whereas smooth muscle actin and desmin were less broadly expressed in hepatic tumors (all P<.001). TFE3 also appeared to be overexpressed in 6 (21%) of 26 hepatic AMLs and 3 (100%) of 3 PEComas, but in none of the renal AMLs. In fluorescence in situ hybridization, although all PEComas harbored a TFE3 rearrangement or amplification, no genetic alterations were found in any hepatic AMLs. In conclusion, although hepatic AMLs and TFE3-rearranged PEComas share pathological features such as the epithelioid appearance and immunoreactivity to TFE3, TFE3 alterations are less likely to be a major molecular event driving tumorigenesis in hepatic AMLs.

Carcinosarcoma of the Extrahepatic Bile Duct Presenting with Stone-like Radiological Findings.

A 73-year-old woman was referred to our hospital due to epigastralgia and jaundice. The radiological findings showed a stone-like tumor in the extrahepatic bile duct. The patient was initially thought to have adenocarcinoma of the bile duct based on the findings of a pathological examination of the bile duct biopsy specimen and underwent pancreaticoduodenectomy; the final diagnosis of the lesion was so-called carcinosarcoma of the extrahepatic bile duct. She died of liver metastasis six months after the surgery. This case suggests that surgical resection is not adequate for achieving a radical cure, and the optimal treatment for extrahepatic bile duct carcinosarcoma should be established immediately.

Gangliocytic paraganglioma: a multi-institutional retrospective study in Japan.

BACKGROUND: Gangliocytic paraganglioma (GP) is an extremely rare benign tumor that commonly arises from the second part of the duodenum. Since GP exhibit neither prominent mitotic activity nor Ki-67 immunoreactivity, this tumor is often misdiagnosed as neuroendocrine tumor (NET) G1 (carcinoid tumor). However, patients with GP may have a better prognosis than patients with NET G1. This fact emphasizes the importance of differentiating GP from NET G1, but few studies have reported the epidemiology and histopathology of GP because of its rarity. To differentiate GP from NET G1 with ease, we conducted a multi-institutional retrospective study analyzing the morphometric and immunohistochemical features of this tumor. METHODS: Since only a limited number of patients with GP could be identified in our institute, we conducted a multi-institutional retrospective study of GP in Japan, which was approved by the Ethics Committee of our medical institute. The obtained tissue sections underwent detailed morphometric and immunohistochemical analyses. Additionally, to differentiate GP from NET G1 with ease, immunohistochemical findings were compared. RESULTS: In our examination of 12 cases of duodenal GP, we found that epithelioid cells of GP exhibited positive reactivity for progesterone receptor and pancreatic polypeptide, whereas tumor cells of NET G1 were completely negative reactivity for both. Additionally, although GP is considered to be an extremely rare NET, we found that four (40.0%) of the ten patients at our institute with duodenal NET G1 actually had GP. CONCLUSIONS: Although GP is regarded as a rare NET, our results suggest that it accounts for a substantial percentage of duodenal NETs. Additionally, confirmation of immunoreactivity for progesterone receptor and pancreatic polypeptide can assist in differentiating GP from NET G1.

Regression of follicular lymphoma of the duodenum following eradication of H. pylori infection.

A 64-year-old woman was referred for an examination of the upper gastrointestinal (GI) tract. Endoscopy showed an elevated lesion in the duodenum with central depression and multiple white granules. Biopsy specimens revealed lymphoid follicles composed predominantly of centrocytes with scattered centroblasts. The tumor cells were positive for bcl-2. The patient was diagnosed with follicular lymphoma and underwent antibiotic therapy for Helicobacter pylori (H. pylori) infection. The regression of the lesion was obvious. After 5.5 years of follow-up, there has been no evidence of recurrence. This case suggests that H. pylori eradication therapy is effective for treating follicular lymphoma in the duodenum.

Extra-gastrointestinal stromal tumor of the pelvic cavity: case report.

Extra-gastrointestinal stromal tumors (E-GISTs) not associated with the alimentary tract in the pelvic cavity are extremely rare. We treated a 49-year-old Japanese man with such an E-GIST in the pelvic cavity who underwent an intrapelvic tumorectomy with a total prostatectomy and partial rectum resection. Gross examination of the specimen revealed an 8.1 × 5 × 4 cm white-grayish mass. Histological findings showed uniform spindle cells with scant atypia that formed interlacing bundles or whorl patterns. These neoplastic cells did not invade adjacent organs, including the gut. Immunohistochemical findings revealed that the neoplastic cells were positive for c-kit, CD34, and vimentin. Molecular analysis showed a c-kit mutation at exon 9 with duplication of Ala and Tyr. Our diagnosis was E-GIST, which belongs to the intermediate group of GIST. Following the operation, we administered imatinib mesylate for 6 months. After stopping for 5 months, it was administered again for local recurrence. We are planning our future strategy for this case including surgical resection as necessary.

[Effectiveness of systemic chemotherapy of GEM+CBDCA+5-FU/LV and hepatic arterial infusion of CDDP in a case of advanced, combined hepatocellular-cholangiocarcinoma with multiple lung metastases].

This patient is a male in his 30's. He was diagnosed as hepatitis B virus-related huge primary liver cancer, 10cm in diameter, located in segment 4, accompanied with left portal thrombus and multiple lung metastases. Ten months after repeating systemic chemotherapy using gemcitabine (GEM)+carboplatin (CBDCA)+5-FU/leucovorin (LV) and hepatic arterial infusion chemotherapy with cisplatin (CDDP) 4 times, extended left lobectomy with caudate lobe could be successfully performed because of marked reducion of the huge tumor. The pathology revealed almost entirely necrotic changes of the main tumor, and the remaining, viable tumor nests showed combined hepatocellular and cholangiocarcinoma. Systemic chemotherapy was repeatedly given afterwards, which kept the pulmonary metastases stable without growth. The present case suggests that systemic chemotherapy using GEM+CBDCA+5-FU/LV may be useful in the multimodal treatment for the combined hepatocellular and cholangiocarcinoma with distant metastases.

A case of mixed ductal-endocrine carcinoma of the pancreas.

A 66-year-old male patient underwent a stomach-preserving pancreatoduodenectomy procedure because of a tumor located around the lower bile duct under the diagnosis of carcinoma of the lower bile duct. The tumor (3.5 × 2.5 cm) was found at the head of the pancreas and had invaded the papillae of Vater at the duodenum. Histology findings indicated both ductal adenocarcinoma and endocrine tumor. The ductal adenocarcinoma component expressed carcinoembryonic antigen, cytokeratin (CK)-19, CK-20, carbohydrate 19-9, and amylase, whereas the endocrine component, which occupied about one-third of the tumor, expressed glucagon, neuron-specific enolase, and chromogranin A. The Ki-67 labeling indices of the two components were 49.7% and 5.3%, respectively. Herein, we present this case of mixed ductal-endocrine carcinoma of the pancreas. Our findings indicate that its aggressive mass may be ascribable to the adenocarcinoma component with a high proliferative potential.

Adenocarcinomas associated with perianal fistulae in Crohn's disease have a rectal, not an anal, immunophenotype.

AIMS: Perianal fistulae are often observed in patients with Crohn's disease (CD), although the development of associated adenocarcinomas is very rare. The origin of adenocarcinomas in perianal fistulae associated with CD remains controversial and includes adjacent anal glands or rectal mucosa. Here, we attempted to determine the origin. METHODS: We performed immunohistochemical analysis on seven cases of adenocarcinomas in perianal fistulae associated with CD using antibodies against mucins (MUCs), cytokeratins (CKs) and the intestine-specific transcription factor CDX2. RESULTS: MUC2 and CK20 were expressed in all seven adenocarcinomas examined. MUC5AC/CLH2, MUC5AC/HGM and CDX2 were positive in four (57%), five (71%), and five (71%) adenocarcinomas, respectively. These proteins were positive in rectal mucosa, and negative in the anal glands. Six of seven adenocarcinomas (86%) were negative for CK7. CK7 was expressed in the anal glands, but not in rectal mucosa. CONCLUSIONS: Adenocarcinomas in perianal fistulae associated with CD showed immunohistochemical phenotypes similar to those of rectal-type mucosa, rather than the anal glands. The adenocarcinomas might originate from cells migrating from the adjacent rectal mucosa to the CD-associated perianal fistulae.

CD44 expression is related to poor prognosis of hypopharyngeal squamous cell carcinoma.

CONCLUSIONS: CD44 expression in hypopharyngeal squamous cell carcinomas (SCCs) is closely associated with poor prognosis for patients. CD44 may serve as a prognostic marker for hypopharyngeal SCCs. OBJECTIVES: CD44, an adhesion molecule binding to extracellular matrix, is believed to participate in the progression of malignancies. To clarify the role of CD44 in the progression of hypopharyngeal SCCs, we examined CD44 expression in relation to clinical parameters in hypopharyngeal SCCs. METHODS: Biopsy specimens of hypopharyngeal SCCs were collected from 40 untreated patients, and their CD44 expression was examined immunohistochemically. Hypopharyngeal SCCs were classified into two groups: CD44-low SCCs comprising < 50% CD44-positive tumor cells and CD44-high SCCs comprising ≥ 50% CD44-positive tumor cells. The relation between CD44 expression and various parameters (clinical T and N stages, distant metastasis, and pathological T and N stages) was analyzed by Fisher's exact test. The relation between CD44 expression and the 5-year disease-free survival (DFS) rate was also analyzed by log rank test. RESULTS: The CD44 expression in hypopharyngeal SCCs was related to pathological N stage, but not to clinical T and N stages and pathological T stage, of the patients. Distant metastasis during the follow-up occurred more frequently in patients with CD44-high SCCs than those with CD44-low SCCs. The 5-year DFS was significantly lower in the former than in the latter.

Utility of real-time diagnosis using contact endoscopy for oral and lingual diseases.

OBJECTIVE: In this study, we prospectively investigated the diagnostic accuracy of CE findings in oral and lingual diseases. METHODS: Between January 2004 and December 2009, CE was used to examine 66 patients with oral and lingual diseases at Hyogo College of Medicine Hospital. Blood vessel networks and superficial cell layers in the mucosal epithelium of normal and lesion sites were observed after staining with 1% methylene blue. Endoscopic diagnoses (CE diagnosis) were compared with subsequent definitive diagnoses based on pathological findings. The sensitivity and specificity for CE diagnosis were calculated. RESULTS: On CE findings, SCC showed the characteristics of absent and tortuous blood vessels, heterogeneous distribution, and increased nucleus/cytoplasm (N/C) ratio. Leukoplakia showed no atypical cells, abundant cornified layers, or cytoplasm without nuclei. Lesions were pathologically classified into three groups: 46 squamous cell carcinomas (SCC), 10 leukoplakias, and 10 other benign lesions (n=66). In 4 patients with SCC, malignancy was underestimated by CE findings. The overall diagnostic rate of the CE was 93.9% (62/66 patients). The sensitivity and specificity of SCC were 0.913 (42/46 patients) and 1.0 (20/20 patients), respectively. CONCLUSION: The usefulness of contact endoscopy (CE) as an in vivo real-time diagnostic instrument that can deliver results prior to pathological confirmation was suggested.

Concomitant adenocarcinoma and colonic non-Hodgkin's lymphoma in a patient with ulcerative colitis: a case report and molecular analysis.

Ulcerative colitis (UC) complicated by colonic lymphoma is rare, although UC is often accompanied by adenocarcinoma of the colon. A concurrent existence of adenocarcinoma and lymphoma in a patient with UC is extremely rare, and has not yet been analyzed at the molecular level. We report a 64-year-old female patient with concomitant adenocarcinoma and diffuse large B-cell lymphoma (DLBCL) in the colon of UC. The genetic changes in these two neoplasms were analyzed. The colon adenocarcinomas had a mutation in MSH6 gene, DNA methylation in CDKN2A gene, and increased microsatellite instability (MSI), although these genetic changes were not recognized in either DLBCL or non-neoplastic UC mucosa. The DLBCL was diagnosed as primary colonic lymphoma, and confirmed Epstein-Barr virus (EBV) infection. The adenocarcinomas and the non-neoplastic UC mucosa were EBV-negative. Our case presented here clearly shows that the development of adenocarcinoma and lymphoma in the colon with UC was caused by individual mechanisms.

Detection of desmoplastic reaction in biopsy specimens is useful for predicting the depth of invasion of early colorectal cancer: a Japanese collaborative study.

BACKGROUND: We have previously demonstrated a relationship between the depth of submucosal invasion (SM depth) and the frequency of lymph node metastasis in resected submucosal invasive colorectal cancers (SICRCs). Here, we assessed the desmoplastic reaction (DR) in pretreatment biopsy specimens of SICRC to predict the SM depth. METHODS: A total of 359 patients with SICRCs, who had undergone surgical or endoscopic mucosal resection, were enrolled. The SM depth of the SICRC lesions was evaluated according to the procedure established by the Japanese Society for Cancer of the Colon and Rectum, and the patients' corresponding pretreatment biopsy specimens were examined histologically to evaluate the prevalence of DR. RESULTS: For pedunculated SICRCs, the prevalence of DR in pretreatment biopsy specimens was significantly higher in moderately differentiated than in well-differentiated adenocarcinomas, but was not significantly related to SM depth. For nonpedunculated SICRCs, the prevalence of DR in pretreatment biopsy specimens was significantly related to histological type, tumor size, and SM depth. When non-pedunculated SICRCs were further divided using a specific cutoff value of 1000 µm for SM depth, the DR positivity rate in pretreatment biopsy specimens was significantly higher in SICRCs with an SM depth of ≥1000 µm (termed "SM massive CRCs") than in cases where the SM depth was <1000 µm (termed "SM slight CRCs"). CONCLUSIONS: Detection of DR in pretreatment biopsy specimens is useful for the prediction of SM depth in nonpedunculated SICRCs, and may be useful for the selection of such cases that would be treatable by endoscopic mucosal resection and endoscopic submucosal dissection (EMR/ESD).

Immunocytochemistry of CD146 is useful to discriminate between malignant pleural mesothelioma and reactive mesothelium.

Malignant pleural mesothelioma is a refractory tumor with poor prognosis associated with asbestos exposure. Pleural effusion is frequently observed in patients with malignant pleural mesothelioma, and cytological analysis is effective to detect malignant pleural mesothelioma. However, cytological discrimination between malignant pleural mesothelioma and reactive mesothelium is often difficult. Increased expression of CD146, a cell adhesion molecule, has been reported to be closely associated with an advanced stage of malignant melanoma, prostate cancer, and ovarian cancer. In this study, to evaluate the diagnostic utility of CD146 for discrimination between malignant pleural mesothelioma and reactive mesothelium, we examined immunocytochemical expression of CD146 in malignant pleural mesothelioma and reactive mesothelium using two clones of CD146 antibody, OJ79 and EPR3208, on smear specimens of effusion fluids. Immunocytochemical stains were semiquantitatively scored on the basis of immunostaining intensity (0, negative; 1, weak positive; 2, moderate positive; and 3, strong positive). CD146 expression was detected in 15 of 16 malignant pleural mesothelioma with median immunostaining score of 3 by OJ79, and in 19 of 21 malignant pleural mesothelioma with median immunostaining score of 2 by EPR3208. Strong immunoreactivity of CD146 was observed at the apposing surfaces of cell-cell interactions on the plasma membrane of mesothelioma cells. In addition, one OJ79-negative case of malignant pleural mesothelioma was positive for CD146 by EPR3208 and two EPR3208-negative cases of malignant pleural mesothelioma were CD146 positive by OJ79, showing that all 23 malignant pleural mesothelioma cases were positive for CD146 by either OJ79 or EPR3208. On the other hand, CD146 expression was undetectable in all reactive mesothelium cases by OJ79 and EPR3208. The sensitivity of OJ79 and EPR3208 was 94 and 90%, respectively, and the specificity was 100% for both clones. We propose that CD146 is a sensitive and specific immunocytochemical marker enabling differential diagnosis of malignant pleural mesothelioma from reactive mesothelium.

Crucial role of impaired Kupffer cell phagocytosis on the decreased Sonazoid-enhanced echogenicity in a liver of a nonalchoholic steatohepatitis rat model.

AIMS: To evaluate the dynamics of Kupffer cell (KC) phagocytosis by performing both in vivo and in vitro studies using Sonazoid (GE Healthcare, Oslo) in a rat nonalcoholic steatohepatitis (NASH) model. METHODS: Contrast enhanced ultrasonography (CEUS) was performed on a rat NASH model induced by a methionine choline deficient diet (MCDD) and control rats, and Sonazoid was used to measure the signal intensity in the liver parenchyma. The uptake of Sonazoid by the KCs was observed by intravital microscopy. Their phagocytic capability was evaluated in vitro using isolated and cultured KCs. The uptake of fluorescein isothiocyanate (FITC)-labeled latex beads was observed and quantitatively analyzed by flow cytometry. RESULTS: In the MCDD group, liver parenchymal enhancement was reduced 20 min after the Sonazoid injection. Microscopic observation of the isolated and cultured KCs revealed that the number of phagocytosed Sonazoid microbubbles was significantly decreased. Confocal laser scanning microscopic (CLSM) observation showed a decrease in the uptake of the latex beads. A decreased phagocytic capacity in the MCDD group was suggested by the quantitative analysis using flow cytometry, as well as by intravital microscopy. CONCLUSIONS: CEUS with Sonazoid is a powerful evaluation tool to diagnose NASH from an early stage of the disease.

Malignant mesothelioma of the peritoneum: case reports and immunohistochemical findings including Ki-67 expression.

A malignant mesothelioma (MM) is an aggressive neoplasm, although some patients have shown long-term survival, and factors related to survival remain uncertain. We present three cases of MM of the peritoneum including autopsy results, in which factors related to long-term survival were investigated. Case 1 was a 69-year-old man who died 6 years after the initial diagnosis. In case 2, a 67-year-old woman came to us with abdominal distention and, despite chemotherapy, died 9 months after the initial diagnosis. The patient in case 3 was a 68-year-old man who also had abdominal distention and died 9 months after the initial diagnosis. We studied the clinicopathological appearance and performed immunohistochemical staining including Ki-67 labeling index (Ki-67 LI) in primary and metastatic sites of these cases. The histological findings of case 1 indicated epithelioid type; case 2 and 3 were of biphasic type. Immunohistochemical results were consistent with MM. The Ki-67 LI value for both primary and metastatic sites of case 1 was significantly lower than those in cases 2 and 3. We consider Ki-67 LI to be a useful prognostic indicator for MM of the peritoneum.

Well-differentiated papillary mesothelioma with invasion to the chest wall.

Well-differentiated papillary mesothelioma (WDPM) is an uncommon tumor with a papillary architecture, bland cytologic features, a tendency toward superficial spread without invasion, and good prognosis with prolonged survival. WDPM occurs primarily in the peritoneum of women, but also rarely in the pleura. We here report a case of 48-year-old woman who developed WDPM in the pleura with no history of asbestos exposure. Tumors were multifocal and widespread with a velvety appearance on the surface of parietal and visceral pleurae resected by extrapleural pneumonectomy (EPP). Tumors showed papillary structures with fibrovascular cores and lined by epithelioid cells. Immunohistochemically, these epithelioid tumor cells were positive for epithelial membrane antigen (EMA), a marker of malignant mesothelioma, with more than 50% positive for p53. Tumor cells microinvaded into subpleural parenchyma of the lung and minimally spread to adipose tissues of the mediastinal lesion. In addition, tumor cells invaded into the chest wall with a trabecular or glandular architecture. Based on these findings, this case is pathologically considered as WDPM of the pleura with malignant potential.

Immunohistochemical analyses of E-cadherin, beta-catenin, CD44s, and CD44v6 expressions, and Ki-67 labeling index in intraductal papillary mucinous neoplasms of the pancreas and associated invasive carcinomas.

We examined the expressions of adhesion molecules (E-cadherin, beta-catenin, CD44s, and CD44v6) and Ki-67 labeling index (Ki-67 LI) in low- and moderate-grade dysplasia and invasive carcinoma components in ten noninvasive intraductal papillary mucinous neoplasms (IPMNs) of the pancreas and eight invasive carcinomas associated with IPMNs of the pancreas using immunohistochemical methods. There was no significant difference in regard to the proportion of components expressing either E-cadherin or beta-catenin in more than 70% of the tumor cells between the low- and moderate-grade dysplasia components. In contrast, the proportion of those in invasive carcinoma components was significantly lower than in low- or moderate-grade dysplasia components. Also, there was no significant difference in the proportion of components expressing CD44s or CD44v6 in more than 5% of tumor cells among low-grade dysplasia, moderate-grade dysplasia, and invasive carcinoma components. In contrast, the Ki-67 LI values increased in the order of low-grade dysplasia, moderate-grade dysplasia, and invasive carcinoma components, with significant differences among them. The present results indicate that carcinoma components are associated with a decrease in tumor cells expressing E-cadherin and beta-catenin and have the highest proliferative activity.

Comparison between mucinous cystic neoplasm and intraductal papillary mucinous neoplasm of the branch duct type of the pancreas with respect to expression of CD10 and cytokeratin 20.

OBJECTIVE: Mucinous cystic neoplasm (MCN) and intraductal papillary mucinous neoplasm of the branch duct type (IPMN-BD) differ in biological and clinical behaviors, but MCN is often misdiagnosed as IPMN-BD. The purpose of this study was to find useful markers for the differential diagnosis of MCN and IPMN-BD. METHODS: Immunohistochemically, the expression of the 2 types of mucin (MUC) 1 (MUC1/DF3 and MUC1/CORE), MUC2, MUC5AC, MUC6, human gastric mucin (HGM), caudal-related homeobox transcription factor 2 (CDX2), CD10, cytokeratin (CK) 7, and CK20 was examined in 7 cases of MCN and 16 cases of IPMN-BD. RESULTS: Expression frequencies in MCN and IPMN-BD were 100% versus 44% for MUC1/DF3, 86% versus 31% for MUC1/CORE, 57% versus 19% for MUC2, 86% versus 100% for MUC5AC, 57% versus 88% for MUC6, 86% versus 100% for HGM, 57% versus 0% for CDX2, 71% versus 0% for CD10, 100% versus 69% for CK7, and 86% versus 6% for CK20. CONCLUSIONS: Mucin 1/DF3, MUC1/CORE, CDX2, CD10, and CK20 were expressed significantly more frequently in MCN than in IPMN-BD. In particular, CD10 and CK20 showed marked differences in immunohistochemical sensitivity and specificity between MCN and IPMN-BD. It is therefore proposed that CD10 and CK20 may be used for the differential diagnosis of MCN and IPMN-BD.