Pathologic significance of peribiliary capillary plexus in gallbladder neoplasm.

AIMS: Significance of peribiliary capillary plexus (PCP) in gallbladder neoplasms remains unclear. Aims are to characterize high-grade biliary intraepithelial neoplasm (BilIN), pyloric gland adenoma (PGA), and intracholecystic papillary neoplasm (ICPN), precursors of gallbladder carcinoma, and to differentiate invasive carcinoma from pseudo-invasive lesions in gallbladder walls, referring to PCP. MATERIALS AND METHODS: High-grade BilIN (38 cases), PGA (5 cases), and ICPN (25 cases) were examined using capillary immunostaining. Non-neoplastic gallbladders were used as controls. RESULTS: In non-neoplastic gallbladders, a single layer of regularly dotted capillaries (PCP) was located beneath lining epithelia and around non-neoplastic glands (NNGs), including Rokitansky-Aschoff sinus (RAS), presenting a two-layer of lining epithelia and PCP. Intra-luminal components of all cases of high-grade BilIN and PGA and one-third of ICPNs presented a two-layer pattern. In the remaining ICPNs, capillaries were irregular and sparse in intraluminal neoplastic components presenting irregular and complicated lesions. Neoplastic glands in gallbladder walls of high-grade BilIN and ICPN were classifiable into 2 types: glands that were underlain by densely dotted capillaries and those that were not, with the latter suggestive of invasive carcinoma, while the former suggestive of non-invasive neoplasms involving NNGs intraepithelially and/or showing an expanding growth into gallbladder wall (pseudo-invasion). CONCLUSION: A two-layer pattern of lining epithelia and underlining capillaries were preserved in all cases of high-grade BilIN and PGA and one-third of ICPN cases. Presence or absence of dotted capillaries around neoplastic glands may be able to be added as a new pathologic feature to differentiate invasive carcinomas from pseudo-invasion in gallbladder wall.

Expression of fibroblast growth factor receptor 2 (FGFR2) in combined hepatocellular-cholangiocarcinoma and intrahepatic cholangiocarcinoma: clinicopathological study.

Genetic alterations including fusions in fibroblast growth factor receptor 2 (FGFR2) are detected in 10-20% of intrahepatic cholangiocarcinoma (iCCA), and FGFR2 inhibitors are effective for the treatment of iCCA. We examined a prevalence of FGFR2 genetic alterations and their clinicopathological significance in combined hepatocellular-cholangiocarcinoma (cHCC-CCA). FGFR2 expression, which is a surrogate marker for FGFR2 genetic alterations, was immunohistochemically assessed in the liver sections from 75 patients with cHCC-CCA, 35 with small duct-type iCCA, 30 with large duct-type iCCA, and 35 with hepatocellular carcinoma (HCC). FGFR2 genetic alterations were detected by reverse transcription-PCR and direct sequence. An association of FGFR2 expression with clinicopathological features was investigated in cHCC-CCAs. FGFR2 expression was detected in significantly more patients with cHCC-CCA (21.3%) and small duct-type iCCA (25.7%), compared to those with large duct-type iCCA (3.3%) and HCC (0%) (p < 0.05). FGFR2-positive cHCC-CCAs were significantly smaller size (p < 0.05), with more predominant cholangiolocarcinoma component (p < 0.01) and less nestin expression (p < 0.05). Genetic alterations of ARID1A and BAP1 and multiple genes were significantly more frequent in FGFR2-positive cHCC-CCAs (p < 0.05). 5'/3' imbalance in FGFR2 genes indicating exon18-truncated FGFR2 was significantly more frequently detected in FGFR2-positive cHCC-CCAs and small duct iCCAs, compared to FGFR2-negative ones (p < 0.05). FGFR2::BICC fusion was detected in a case of cHCC-CCAs. FGFR2 genetic alterations may be prevalent in cHCC-CCAs as well as small duct-type iCCAs, which suggest cHCC-CCAs may also be a possible therapeutic target of FGFR2 inhibitors.

Interobserver agreement of pathologic classification and grading of tumoral intraductal pre-invasive neoplasms of the bile duct.

Current WHO terminology and recent publications have classified tumoral (grossly visible) intraductal pre-invasive neoplasms of bile duct (TIDN) into three categories: intraductal papillary neoplasm of bile duct (IPNB), intraductal papillary oncocytic neoplasm (IOPN), and intraductal tubulopapillary neoplasm (ITPN). A total of 227 cases of TIDN and related lesions ≥3 mm in height were examined by 10 biliary pathologists referring to these 3 categories and two pathologic gradings: two-tiered system (low- and high-grade dysplasia) and modified types 1 and 2 subclassification. Among them, IPNB was the most frequent (183 cases), followed by IOPN (28 cases), while ITPN was rare (2 cases), and interobserver agreement in this classification was "substantial" (κ-value, 0.657). The interobserver agreement of two-tiered grading system of TIDN was "slight" (κ-value, 0.201), while that of modified types 1 and 2 subclassification was "moderate" (κ-value, 0.515), and 42 % were of type 1, and 58 % were of type 2. Type 1 TIDN showed occasional stromal invasion (6.7 %), whereas type 2 TIDN was frequently associated with stromal invasion (49.6 %) (p < 0.01). In conclusion, the classification of TIDN into three categories and modified types 1 and 2 subclassification are a practically applicable classification and grading system for TIDN.

Nestin may be a candidate marker for differential diagnosis between small duct type and large duct type intrahepatic cholangiocarcinomas.

BACKGROUNDS/AIMS: Intrahepatic cholangiocarcinoma (iCCA) is subclassified into small and large duct types. These two subtypes show distinct differences in various clinicopathological features and possible cell origin and pathways of carcinogenesis, however, a differential diagnosis may be sometimes difficult. Given the type IV intermediate filament, Nestin, may be a candidate diagnostic marker for combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and small duct type iCCAs, the significance of nestin as a differential diagnostic marker between small and large duct types of iCCAs was addressed in the present study. METHODS: Nestin expression was immunohistochemically assessed in the sections from 36 patients with small duct-type iCCA, 30 with large duct-type iCCA, and 27 with extrahepatic cholangiocarcinoma (CCA). Nestin expression and its relationship with clinicopathological features and genetic alterations were investigated in small duct type iCCAs. RESULTS: Nestin expression was detected in 17 small duct type iCCAs (47.2%), one large duct type iCCA (3.8%) and zero extrahepatic CCA. Nestin expression was significantly more frequent in the patients with small duct type iCCAs than in those with large duct type iCCA and extrahepatic CCA (p < 0.01). In 10 liver biopsies, all samples with nestin expression were small duct type iCCAs. Nestin-positive small duct type iCCAs were characterized by a higher histological grade, compared to Nestin-negative small duct type iCCAs (p < 0.01). Nestin-positive small duct type iCCAs tended to have 2 or more genetic alterations, but there was no statistic difference (p > 0.05). CONCLUSION: Different nestin expression may reflect differences between small duct type iCCA and large duct type/extrahepatic CCA and may be a useful diagnostic marker for small duct type iCCAs.

Bile duct adenoma and small-sized small duct type intrahepatic cholangiocarcinoma show distinct differences in genetic alterations, expression of IMP3 and EZH2 and stromal and inflammatory components.

AIMS: Given that bile duct adenoma was significantly more prevalent in the liver with small duct type intrahepatic cholangiocarcinoma (small duct iCCA), compared to other primary liver carcinomas, we examined the possibility of bile duct adenoma as a precursor of small duct iCCA by analysing genetic alterations and other features in bile duct adenomas. METHODS AND RESULTS: Subjects included 33 bile duct adenomas and 17 small-sized (up to 2 cm in diameter) small duct iCCAs. Genetic alterations were examined by direct sequencing for hot-spot regions and immunohistochemical staining. The expression of p16INK4a , EZH2 and IMP3 and stromal and inflammatory components were also examined. Genetic alterations examined including BRAF were not detected in bile duct adenomas, whereas genetic alterations of p53 (47%), ARID1A (41%), PBRM1 (12%), MTAP (12%), IDH1 (6%), KRAS (6%) and TERT promoter (6%) were detected in 16 small-sized small duct iCCA (94%) (P < 0.01). The expression of IMP3 and EZH2 was not detected in bile duct adenomas, whereas it was detected in most small duct iCCA (94%) (P < 0.01). Immature stroma and neutrophilic infiltration were significantly more prevalent in small duct iCCA, compared to bile duct adenoma (P < 0.01). CONCLUSION: Bile duct adenomas and small-sized small duct iCCAs show distinct differences in genetic alterations, expression of IMP3 and EZH2 and stromal and inflammatory components. There was no evidence suggesting that bile duct adenoma is a precursor of small duct iCCA. Immunohistochemical staining for IMP3, EZH2, p53, ARID1A and MTAP may be useful for differential diagnosis between bile duct adenomas and small duct iCCAs.

An involvement of Hippo-yes-associated protein pathway in biliary epithelial senescence in primary biliary cholangitis.

BACKGROUND & AIMS: Accumulating evidence suggest that Hippo-yes-associated protein (YAP) pathway plays important roles in development and repair after injuries in biliary system. We disclosed that senescent biliary epithelial cells (BECs) participate in the pathogenesis of primary biliary cholangitis (PBC). We hypothesized that dysregulation of Hippo-YAP pathway may be associated with biliary epithelial senescence in pathogenesis of PBC. APPROACH & RESULTS: Cellular senescence was induced in cultured BECs by treatment with serum depletion or glycochenodeoxycholic acid. The expression and activity of YAP1 were significantly decreased in senescent BECs (p<0.01). Cellular senescence and apoptosis were significantly increased (p<0.01) and a proliferation activity and a 3D-cyst formation activity were significantly decreased (p<0.01) by a knockdown of YAP1 in BECs. The expression of YAP1 were immunohistochemically determined in livers taken from the patients with PBC (n = 79) and 79 control diseased and normal livers and its association with senescent markers p16INK4a and p21WAF1/Cip1 was analyzed. The nuclear expression of YAP1, which indicates activation of YAP1, was significantly decreased in BECs in small bile ducts involved in cholangitis and ductular reactions in PBC, compared to control livers (p<0.01). The decreased expression of YAP1 was seen in senescent BECs showing expression of p16INK4a and p21WAF1/Cip1 in bile duct lesions. CONCLUSION: Dysregulation of Hippo-YAP1 pathway may be involved in the pathogenesis of PBC in association with biliary epithelial senescence.

Pathological survey of precursor lesions in cholangiocarcinoma.

BACKGROUND: To clarify the pathological significance of two precursors (high-grade biliary intraepithelial neoplasm [BilIN] and intraductal papillary neoplasm of bile duct [IPNB]) in cholangiocarcinomas (CCAs). METHODS: Ninety-one cases of CCA (47 distal CCAs [dCCAs], 31 perihilar CCAs [pCCAs] and 13 intrahepatic CCAs of large duct type [LD-iCCAs]) were examined for their association with precursors. Neoplastic intraepithelial lesions without underlying infiltrating carcinoma in the surrounding mucosa of CCAs were considered to reflect high-grade BilIN. High-grade BilIN and IPNB were subdivided into gastric, biliary, intestinal and oncocytic subtypes, while CCAs were subdivided into gastrobiliary, intestinal and oncocytic subtypes. The postoperative overall survival (OS) was examined. RESULTS: Fifty-four and 8 of 91 CCAs were associated with high-grade BilIN and IPNB, respectively, while these precursors were unidentifiable in the remaining CCAs. A majority of CCAs were of the gastrobiliary subtype, while the intestinal subtype was occasionally detected, and the oncocytic subtype was rare. CCAs with high-grade BilIN showed a similar postoperative OS to CCAs without precursors, while CCAs with IPNB showed a favorable postoperative OS compared to CCAs without precursors. CONCLUSIONS: CCAs were frequently associated with precursors; high-grade BilIN may be a major precursor and IPNB a minor one. CCAs with IPNB showed a favorable postoperative OS compared to CCAs with high-grade BilIN.

Intraepithelial involvement of non-neoplastic glands in papillary preinvasive neoplasms of the biliary tract: a potential diagnostic pitfall.

Intracholecystic papillary neoplasms of the gallbladder (ICPN) and intraductal papillary neoplasms of the bile duct (IPNB) show intramural neoplastic growths in addition to intraluminal papillary or polypoid neoplastic growth. Such intramural growths include intraepithelial involvement of non-neoplastic glands by preinvasive neoplastic epithelia (glandular involvement) as well as stromal invasive carcinoma. A total of 29 ICPN cases and 84 IPNB cases were pathologically examined for their glandular involvement. Glandular involvement was characterized by intramural neoplastic glands (1) showing cytological and phenotypical similarities to intraluminal preinvasive papillary neoplasms and (2) showing reminiscent configurations of non-neoplastic glands, such as (i) a mixture of preinvasive neoplastic epithelia and non-neoplastic epithelia within the same glands, (ii) neoplastic glands close to or within clustered non-neoplastic glands, or (iii) continuous growth of intraluminal preinvasive neoplastic glands into the walls. Such glandular involvement was found in 16 of 29 ICPN and 48 of 84 IPNB, and 15 of the former and 28 of the latter were not associated with invasive carcinoma. Non-invasive ICPN and IPNB with glandular involvement showed a favorable postoperative overall survival (OS). Glandular involvement by preinvasive neoplastic epithelia was frequently found in ICPN and IPNB. Such lesions may be diagnostic pitfalls in ICPN and IPNB referring to invasion. Glandular involvement without invasive carcinoma was not associated with an unfavorable postoperative OS in ICPN and IPNB. Recognition of glandular involvement may thus prevent overestimation of invasive carcinoma in ICPN and IPNB.

Intracholecystic papillary neoplasm acquiring malignant characteristics and leading to multiple liver metastases: A case report.

The mechanisms underlying the progression of intracholecystic papillary neoplasms (ICPNs) to gallbladder cancer and invasive cancer remain relatively unclear. In the present case, metastatic liver tumors were suspected in an 83-year-old man at presentation; however, the primary tumor was unknown. The patient died shortly thereafter as a result of rapid tumor progression. An autopsy revealed multiple liver, lung, and lymph node metastases. Additionally, a fragile papillary tumor with a high-grade dysplastic epithelium with tubulopapillary morphology and admixed foci of a low-grade dysplastic epithelium were detected at the fundus of the gallbladder. The well-differentiated tubular adenocarcinoma had extensively invaded the wall's granular mucosal surface along with the solitary papillary tumor. Based on pathological findings, a diagnosis of an ICPN with an associated invasive carcinoma was established. This case is novel because it showed that an ICPN can progress aggressively.

Pathologies of Precursor Lesions of Biliary Tract Carcinoma.

Carcinomas and precursor lesions of the biliary tract belong to a spectrum of pancreatobiliary neoplasms that share common histology and cell lineages. Over the past two decades, preinvasive precursors to biliary tract carcinomas (BTCs) have been identified such as high-grade biliary intraepithelial neoplasm (high-grade BilIN), intraductal papillary neoplasm of bile duct (IPNB) and intracholecystic papillary neoplasm of the gallbladder (ICPN). While a majority of these precursors may arise from the biliary tract mucosa, some originate from the peribiliary glands and Rokitansky-Aschoff sinuses in the walls of the biliary tract. High-grade BilIN is a microscopically identifiable intraepithelial neoplasm of the biliary tract, whereas IPNB and ICPN are grossly visible intraductal or intraluminal preinvasive neoplasms in the bile duct and gallbladder, respectively. These neoplasms show characteristic histologic features according to four cell lineages and two-tiered grading, and show intraepithelial spreading to the surrounding mucosa and involve non-neoplastic glands in the walls of the biliary tract. These precursors are not infrequently associated with stromal invasion, and high-grade BilIN, in particular, are frequently identified in the surrounding mucosa of BTCs. Taken together, it seems likely that progression from these precursors to invasive carcinoma is a major process in biliary carcinogenesis.

Pathologic patterns of invasive carcinoma associated with intraductal papillary neoplasms of bile duct (IPNB).

The pathologic features of invasive carcinoma associated with IPNB remain to be clarified. By using 82 cases of IPNB, the pathologic spectrum of associated invasive carcinoma and its correlation with their post-operative overall survival (OS) were examined. Invasive carcinoma was found in 52 cases (63 %) of IPNB and was classifiable into three patterns (patterns A, B and C). Pattern A was characterized by microscopic foci of invasive carcinoma in the fibrovascular stalks or confined to the bile duct mucosa and wall beneath the intraluminal pre-invasive neoplastic components of IPNB (23 cases) and pattern B by invasive carcinoma in the periductal connective tissue and in the adjacent organ(s) mainly near or beneath the intraluminal component(s) of IPNB (15 cases). Pattern C showed nodular invasive carcinoma considerably involving the intraluminal pre-invasive components and the bile duct mucosa and wall adjacent to the intraluminal pre-invasive components of IPNB (14 cases). Recognition of these three patterns of invasive carcinoma associated with IPNB may expand the pathologic spectrum of IPNB. IPNBs without invasive carcinoma showed a favorable post-operative-OS compared with those with invasion as a whole and those of pattern B and C, respectively, but showed a similar post-operative-OS to that of pattern A. IPNB of pattern B and C showed an unfavorable post-operative outcome, though there was no difference between pattern B and C. Understanding of the pathologic spectrum of associated invasive carcinoma may facilitate further pathological analysis of IPNB.

DNMT1 Expression and DNA Methylation in Intraductal Papillary Neoplasms of the Bile Duct.

BACKGROUND/AIM: Intraductal papillary neoplasms of the bile duct (IPNB) are histologically and clinically classified as type 1 and 2. This study aimed to identify the differences between these two types. MATERIALS AND METHODS: Based on multiple gene expression analysis (MGEA) using type 1, type 2, and pancreatic intraductal papillary mucinous neoplasms (n=4, 6, and 5, respectively), immunohistochemistry of DNMT1 and methylation-specific PCR for p16, APC, BRCA1, hMLH1, TIMP3, and SOX17 were performed on type 1 and 2 IPNBs (n=14, each). RESULTS: The DNMT1 protein was highly expressed (p<0.001) in 28.6% of type 1 cases and all type 2 cases. The DNA methylation ratio for the six genes in total as well as for SOX17 was lower in type 1 than in type 2 (p<0.05 each). CONCLUSION: Type 2 IPNB showed increased DNMT1 protein expression and increased DNA methylation frequency of the examined tumor suppressor genes compared to type 1. DNMT1 IHC may be helpful in discriminating between these two types.

Identification of circulating microRNAs as potential biomarkers for hepatic necroinflammation in patients with autoimmune hepatitis.

OBJECTIVE: MicroRNAs (miRNAs) are implicated in the pathogenesis of autoimmune diseases and could be biomarkers of disease activity. This study aimed to identify highly expressed circulating miRNAs in patients with autoimmune hepatitis (AIH) and to evaluate their association with clinical characteristics. METHODS: Microarray analyses were performed, and miRNA expression profiling for AIH, primary biliary cholangitis (PBC) and overlap syndrome (OS) using the serum of patients and healthy individuals was done. Samples were divided into discovery and test sets to identify candidate miRNAs that could discriminate AIH from PBC; the former included 21 AIH and 23 PBC samples, while the latter included five AIH and eight PBC samples. RESULTS: Among 11 candidate miRNAs extracted in the discovery set, 4 (miR-3196, miR-6125, miR-4725-3 p and miR-4634) were specifically and highly expressed in patients with AIH in the test set. These four miRNAs discriminated AIH from PBC with high sensitivity (0.80-1.00) and specificity (0.88-1.00). In situ hybridisation analysis revealed that these miRNAs were expressed in the cytoplasm of hepatocytes in patients with AIH. Their expression levels were highest in untreated patients with AIH, followed by those in untreated patients with OS. They drastically or moderately decreased after prednisolone treatment. Histological analysis demonstrated that the expression levels of miR-3196, miR-6125 and miR-4634 in patients with AIH and OS were correlated with severe hepatic necroinflammatory activity. CONCLUSION: These circulating miRNAs are suggested to reflect hepatic necroinflammatory activity and serve as AIH-related and treatment-responsive biomarkers. These miRNAs could be beneficial in developing new therapeutic strategies for AIH.

Concurrent Activation of Kras and Canonical Wnt Signaling Induces Premalignant Lesions That Progress to Extrahepatic Biliary Cancer in Mice.

Biliary cancer has long been known to carry a poor prognosis, yet the molecular pathogenesis of carcinoma of the extrahepatic biliary system and its precursor lesions remains elusive. Here we investigated the role of Kras and canonical Wnt pathways in the tumorigenesis of the extrahepatic bile duct (EHBD) and gall bladder (GB). In mice, concurrent activation of Kras and Wnt pathways induced biliary neoplasms that resembled human intracholecystic papillary-tubular neoplasm (ICPN) and biliary intraepithelial neoplasia (BilIN), putative precursors to invasive biliary cancer. At a low frequency, these lesions progressed to adenocarcinoma in a xenograft model, establishing them as precancerous lesions. Global gene expression analysis revealed increased expression of genes associated with c-Myc and TGFß pathways in mutant biliary spheroids. Silencing or pharmacologic inhibition of c-Myc suppressed proliferation of mutant biliary spheroids, whereas silencing of Smad4/Tgfbr2 or pharmacologic inhibition of TGFß signaling increased proliferation of mutant biliary spheroids and cancer formation in vivo. Human ICPNs displayed activated Kras and Wnt signals and c-Myc and TGFß pathways. Thus, these data provide direct evidence that concurrent activation of the Kras and canonical Wnt pathways results in formation of ICPN and BilIN, which could develop into biliary cancer. SIGNIFICANCE: This work shows how dysregulation of canonical cell growth pathways drives precursors to biliary cancers and identifies several molecular vulnerabilities as potential therapeutic targets in these precursors to prevent oncogenic progression.

Polypoid invasive carcinoma of bile duct: report of four cases.

Recently, "polypoid invasive carcinoma (PICA)" showing grossly visible polypoid, invasive carcinoma with no adenoma component was proposed as a neoplastic polyp of the gallbladder. Herein, we report four cases of PICA of the bile duct. PICA cases of bile duct showed single, sessile polypoid growth grossly, and polypoid components were composed of invasive carcinoma of papillary/tubular patterns with active desmoplasia, and invaded directly and continuously into the bile duct wall and periductal tissue. While PICA and other intraductal papillary neoplasm of bile duct (IPNB) shared several features, PICA showed an invasive carcinoma growing in the duct lumen and also invading into the bile duct wall, thus different from IPNB which is the intraluminal polypoid, preinvasive epithelial neoplasia with back-to-back epithelial units. Taken together, PICA and IPNB could be differentiated from each other.

Association of precursors with invasive adenocarcinoma of the gallbladder: A clinicopathological study.

BACKGROUND: The current WHO classification proposed high-grade biliary intraepithelial neoplasm (BilIN) and intracholecystic papillary neoplasm (ICPN) as precursors of the gallbladder carcinoma (GBC). Herein, conventional GBCs (cGBCs) were pathologically examined with respect to these two precursors. METHODS: Forty-seven cases of GBC with grossly visible invasions were collected from Fukui Saiseikai Hospital. The association of two precursors was analyzed referring to pathologic features of cGBCs and post-operative survival. RESULTS: 20 cGBCa (42.6%) were associated with either of two precursors in the surrounding mucosa: high-grade BilIN in 15 cases (31.9%) or ICPN in 5 cases (10.6%). Association of precursors was not related to gross types of and histological differentiation of cGBC. cGBCs without precursors showed frequent vascular/perineural invasion and lymph node metastasis, though cGBCs with and without precursors presented a similar post-operative survival. High-grade BilIN and ICPN associated with cGBCs showed more complicated cytoarchitectural features compared with those with no or focal invasion. CONCLUSION: More than 40% of cGBCs were associated with high-grade BilIN or ICPN, and the former was a frequent precursor. cGBCs without precursors showed aggressive pathologic features. Clinical detection of these precursors may make early treatment of cGBCs possible.

Polypoid invasive carcinoma of the gallbladder-Another challenging polypoid neoplasm.

BACKGROUND: Invasive gallbladder carcinoma generally presents as nodular-sclerosing growth. Recently, "polypoid invasive carcinoma (PICA)" showing grossly visible polypoid neoplasm and histologically invasive carcinoma with no adenomatous components was proposed as a neoplastic polyp of the gallbladder. METHODS: We herein report five cases of PICA collected from 49 cases of invasive gallbladder carcinoma in comparison with another polypoid preinvasive neoplasm of gallbladder, intracholecystic papillary neoplasm (ICPN). RESULTS: Polypoid invasive carcinomas were composed of four males and one female with an average age of 74 years. Polypoid lesions were sessile (height ranging from 6 to 10 mm and the largest diameter ranging from 12 to 40 mm), and histologically, polypoid neoplasms presented papillary configuration containing tubular and cribriform components with thin inflammatory, fibrotic stroma. Polypoid carcinoma invaded directly and continuously into the gallbladder wall with destruction of the muscle layer. These patterns of PICA were different from ICPN, showing papillary patterns containing tubular components with fine fibrovascular stalks and with occasional focal stromal invasion but with preserved muscle layer. Post-operative outcome was not favorable in PICA but was favorable in ICPN. CONCLUSIONS: Polypoid invasive carcinoma shared several pathological features with ICPN, such as intraluminal polypoid pattern with papillary configurations, but PICAs were invasive adenocarcinoma with destruction of muscle layer while ICPNs were preinvasive neoplasm with occasional focal stromal invasion, thus both should be differentiated from each other.

Pathological features of pyloric gland adenoma of the gallbladder in comparison with gastric subtype of intracholecystic papillary neoplasm.

BACKGROUND AND AIMS: Pyloric gland adenoma (PGA) of the gallbladder is a polypoid, preinvasive epithelial neoplasm composed of uniform back-to-back, pyloric glands in a tubular configuration. Intracholecystic papillary neoplasm (ICPN), another preinvasive grossly visible neoplasm of the gallbladder, is subdividable into four subtypes, including gastric subtype. In this study, PGA was reappraised referring to gastric subtype of ICPN (gICPN). MATERIALS AND METHODS: PGA and gICPN pathologically defined by WHO 2019 classification were surveyed in a total of 104 cases of gallbladder epithelial neoplasms of our Hospital (2002 January to 2021 May) and were pathologically and immunohistochemically compared. RESULTS: PGA (7 cases) was characterized by i) a well-demarcated, polypoid lesion and ii) packed tubular components resembling pyloric glands. gICPNs (14 cases) were subdivided into i) pyloric gland predominant (2 cases), ii) foveola predominant (6 cases) and iii) mixed foveola and pyloric gland type (6 cases). gICPNs were also divided into a solitary, polypoid lesion with well demarcation from the surrounding mucosa (5 cases) and a conglomerated polypoid and granular lesions with poor demarcation (9 cases). PGA shared gross and histologic features with solitary, polypoid gICPNs, and PGA could be regarded as solitary gICPN predominantly composed of pyloric glands. Nuclear expression of ß-catenin was found in 6 of 7 PGA, but absent in gICPN, including solitary, polypoid gICPN. CONCLUSION: PGA could correspond to a solitary gICPN mainly composed of pyloric glands, but may undergo a different molecular pathway from gICPN.

Characterization of high-grade biliary intraepithelial neoplasm of the gallbladder in comparison with intracholecystic papillary neoplasm.

Biliary intraepithelial neoplasm (BilIN) is characterized by a microscopically identifiable preinvasive neoplasm of the biliary tract. In this study, the high-grade BilIN of gallbladder was examined pathologically and compared with the intracholecystic papillary neoplasm (ICPN) of gallbladder. Sixteen high-grade BilINs (height <0.5 cm) collected from 2297 cholecystectomies (0.7%) and another three cases (19 cases total) were examined and compared with 34 cases of ICPN (greatest diameter ≥1 cm and height ≥0.5 cm). High-grade BilINs were incidentally found in 11 cholecystectomies, and the remaining eight were cholecystectomized in cases with a preoperative diagnosis of carcinoma. The largest diameter ranged from 0.5 to 6 cm. While 13 cases were recognized grossly as clustered granular and rough mucosa, the remaining were almost unrecognizable. Histologically, the high-grade BilINs showed intraepithelial neoplastic growth. Furthermore, they frequently showed intraepithelial replacement growth to non-neoplastic glands and cystic lesions in the gallbladder. The lesions presented with flat, wave or fold-like patterns, including tubular components. Short papillary components were also found in 13 cases. Gastric and biliary subtypes were frequent. Several foci of stromal invasion were found in the short papillary components in three cases. The lower polypoid or granular parts of conglomerated ICPNs showed intraepithelial neoplastic lesions sharing many features with high-grade BilINs with short papillary components. In conclusion, high-grade BilINs showed intraepithelial growth of neoplastic epithelia involving the mucosa. A morphologic continuum was noted between high-grade BilINs with short papillary components and conglomerated ICPNs, suggesting that conglomerated ICPNs may arise from high-grade BilINs with short papillary components.

Apical Membrane Expression of Distinct Sulfated Glycans Is a Characteristic Feature of Ductules and Their Reactive and Neoplastic Counterparts.

Intrahepatic bile ducts transport bile between bile canaliculi and the extrahepatic bile duct. The luminal surface of this tract is lined by a layer of biliary epithelial cells, or cholangiocytes, which secrete mucins consisting of scaffold proteins and O-glycosidically linked carbohydrate side chains. Although mucin core proteins have been extensively investigated, the structure and function of carbohydrate side chains have not. Here, we demonstrate that distinct sulfated glycans positive for MECA-79, R-10G, and 297-11A, but not 5D4, monoclonal antibodies are expressed in the cytoplasm of cells of large-sized ducts and in the apical membrane of cells in ductules, and that R-10G immunolabeling is partially eliminated by endo-ß-galactosidase digestion, supporting the presence of N-acetylglucosamine-6-O-sulfated N-acetyllactosamine structures. We observed comparable apical membrane-predominant staining in ductular reactions seen during regeneration that occurs in various liver diseases and in cholangiolocarcinoma, a subtype of small duct-type intrahepatic cholangiocarcinoma (iCCA). Apical membrane expression of distinct sulfated glycans in large duct-type iCCA was negligible. Intriguingly, under pathological conditions, endo-ß-galactosidase digestion almost completely eliminated R-10G immunoreactivity. These findings suggest that apical membrane expression of distinct sulfated glycans is a characteristic feature of ductules and their reactive and neoplastic counterparts.