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Reports of Helicobacter pylori (Hp)-naïve gastric neoplasm (HpNGN) cases have been rapidly increasing due to the recent increase in the Hp-naïve population in Japan. Most HpNGNs exhibit the gastric immunophenotype and a low malignant potential regardless of histological type. Especially, foveolar-type gastric adenoma (FGA) and intestinal-type gastric dysplasia (IGD) rarely progress to invasive carcinoma. FGA is a foveolar epithelial neoplasm that occurs in the fundic gland (oxyntic gland) mucosa and is classified as the flat type or raspberry type (FGA-RA). The flat type is a large, whitish flatly elevated lesion while FGA-RA is a small reddish polyp. Genomically, the flat type is characterized by APC and KRAS gene mutations and FGA-RA by a common single nucleotide variant in the KLF4 gene. This KLF4 single-nucleotide variant reportedly induces gastric foveolar epithelial tumorigenesis and activates both cell proliferation and apoptosis, leading to its slow-growing nature. IGD consists of an intestinalized epithelial dysplasia that develops in the pyloric gland mucosa, characterized as a superficial depressed lesion surrounded by raised mucosa showing a gastritis-like appearance. Immunohistochemically, it exhibits an intestinal or gastrointestinal phenotype and, frequently, p53 overexpression. Thus, IGD shows unique characteristics in HpNGNs and a potential multistep tumorigenic process., (© 2024 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

Barrett's esophagus is considered a precancerous lesion of esophageal adenocarcinoma (EAC). Long-segment Barrett's esophagus, which is generally associated with intestinal metaplasia, has a higher rate of carcinogenesis than short-segment Barrett's esophagus, which is mainly composed of cardiac-type mucosa. However, a large number of cases reportedly develop EAC from the cardiac-type mucosa which has the potential to involve intestinal phenotypes. There is no consensus regarding whether the definition of Barrett's epithelium should include intestinal metaplasia. Basic researches using rodent models have provided information regarding the origins of Barrett's epithelium. Nevertheless, it remains unclear whether differentiated gastric columnar epithelium or stratified esophageal squamous epithelium undergo transdifferentiation into the intestinal-type columnar epithelium, transcommittment into the columnar epithelium, or whether the other pathways exist. Reflux of duodenal fluid including bile acids into the stomach may occur when an individual lies down after eating, which could cause the digestive juices to collect in the fornix of the stomach. N-nitroso-bile acids are produced with nitrites that are secreted from the salivary glands, and bile acids can drive expression of pro-inflammatory cytokines via EGFR or the NF-κB pathway. These steps may contribute significantly to carcinogenesis., (© 2019 The Authors. Pathology International published by the Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

A fundic gland polyp (FGP) is a common gastric polyp. Intraepithelial neoplasia in FGPs, referred to as FGP with dysplasia, is often seen in patients with familial adenomatous polyposis (FAP). In sporadic FGPs, low-grade dysplasia (LGD) is rare, and high-grade dysplasia (HGD) or carcinoma arising from sporadic FGPs is extremely rare. Because of this rarity, the prognosis and appropriate management of these lesions have not been clarified. In the present case, a sporadic FGP with LGD did not develop into invasive carcinoma, but contained foci of HGD 14 years after diagnosis. The biopsy specimen of the polyp taken at the first esophagogastroduodenoscopy 15 years earlier was diagnosed as FGP without dysplasia. At the second histological examination, LGD was found. Because the polyp increased in size during proton pump inhibitor therapy for 14 years, endoscopic mucosal resection was performed. The pathological diagnosis of the resected specimen was FGP with HGD mixed in LGD, with no invasive carcinoma. Dysplasia in FGPs might have less malignant potential regardless of dysplasia or size., (© 2018 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVGC) is defined as a neoplasm comprising monoclonal proliferation of EBV-infected gastric epithelial cells. Although the typical histology is gastric carcinoma with lymphoid stroma (GCLS), the histologic features of the tumor vary. We report herein the case of a 78-year-old man with multiple simultaneous EBVGCs revealing different histopathologic morphologies; one was mixed adenoneuroendocrine carcinoma (MANEC), and the other was GCLS. Both tumor types exhibited positive results for EBV in situ hybridization. To the best of our knowledge, this represents the first report of EBVGC showing neuroendocrine differentiation. Immunohistochemistry also revealed a loss of gastrointestinal features, including CDX2, MUC5AC, and MUC6 expression, among tumor cells from the neuroendocrine component of the MANEC. We describe the pathologic features of this rare neoplasm and discuss the mechanisms underlying the neuroendocrine differentiation of EBVGC cells, along with providing a brief review of the literature., (© 2017 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.)

We here report on two rare cases of intrafollicular classical Hodgkin lymphoma (CHL). Case 1 was a 34-year-old man who underwent left supraclavicular lymph node biopsy. Case 2 was a 28-year-old woman who underwent surgical resection of an anterior mediastinal mass. The histology and microenvironment of both specimens resembled those of nodular lymphocyte predominant Hodgkin lymphoma. Nodular architecture was observed, which comprised normal-appearing small lymphocytes and scattered lymphocyte predominant (LP)-like cells. CD23(+) follicular dendritic cell meshworks were present in the nodules, surrounded by a mantle zone containing IgD(+) B cells. The LP-like cells were ringed by CD3(+) and PD-1(+) T cells, and numerous CD20(+) B cells were present in the background. However, the immunophenotypes of the LP-like cells resembled those of Hodgkin/Reed-Sternberg cells of CHL; they were positive for CD15, CD30, and PAX5, and negative for CD20, Bcl6, Oct2, and Bob1. These histopathological findings indicate that CHL can be derived from the germinal center., (© 2014 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

To investigate the clinicopathological and prognostic significance of a nodular pattern and immunophenotypes in primary mediastinal large B-cell lymphoma (PMBL), histopathological features, including a nodular pattern and immunophenotypes, were analyzed in 58 Japanese PMBL patients. The patients were 23 men and 35 women with a median age of 31 years. The 4-year progression free survival (PFS) rate was 78%, and the 4-year overall survival (OS) rate was 89%. Among the histopathological and immunohistochemical features, Bcl6(+) (P = 0.013), MUM1(+) (P = 0.091), and pale cytoplasm (P = 0.064) were favorable prognostic indicators of PFS, and Bcl6(+) (P = 0.051) and MUM1(+) (P = 0.07) were favorable prognostic indicators of OS. Patients with Bcl2 negativity (n = 11) had 4-year PFS and OS rates of 100%. Histologically, a nodular pattern, resembling nodular sclerosis classical Hodgkin lymphoma (CHL), was observed in 22 patients (38%). However, this was not a significant prognostic indicator. In conclusion, Bcl6(+) , MUM1(+) , Bcl2(-) , and pale cytoplasm are candidate favorable prognostic indicators for PMBL and should be further examined in larger studies. We suggest that PMBL with a nodular pattern may belong to the same histological spectrum as nodular sclerosis CHL., (© 2014 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

It has been speculated that intraductal dissemination, via the pancreatic duct, bile duct, or mammary duct, is a unique form of cancer cell spread. However, clinical evidence to confirm this form of dissemination has been lacking. Here we report a case of papillary adenocarcinoma of the ampulla of Vater in which retrograde dissemination to the pancreatic duct was strongly suggested. A 79-year-old woman underwent pancreatoduodenectomy for a 22 mm microinvasive papillary adenocarcinoma of the ampulla. Multiple carcinomas in situ were found in the pancreatic duct distant from the ampulla. Seven months later, she underwent a second operation for a recurrent papillary adenocarcinoma at the pancreato-jejunal anastomosis showing exophytic and expansive growth into the jejunal lumen that connected to an intraductal adenocarcinoma in the pancreatic body. None of these tumors showed invasive growth, or vascular or neural invasion, being separate from each other but sharing identical histological, immunohistochemical, and molecular features; papillary growth, a pancreatobiliary phenotype, the same pattern of genomic loss of heterozygosity, and no mutation of the KRAS, TP53, and GNAS genes. These results imply that this papillary adenocarcinoma of the ampulla of Vater had disseminated to the pancreatic duct in a retrograde manner and recurred in the remnant pancreas., (© 2014 The Authors. Pathology International © 2014 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

We previously reported a relationship between depth of submucosal invasion of early colorectal carcinomas and desmoplastic reaction (DR). However, poor inter-observer agreement on the histopathological diagnosis of DR in biopsy specimens with hematoxylin and eosin (H&E) staining has been the major critique of this tool. In this study, reproducibility of the histopathological diagnosis of DR was evaluated. Furthermore, we investigated the possible improvement of the reproducibility after education about histological characteristics and tried to identify histological characteristics that are most important in the recognition of DR. A total of 34 H&E stained slides were included in this study and analyzed by three pathologists. Slides were reviewed before and after education about histological characteristics of DR. Kappa statistics were used to compare the inter-observer variability. We investigated the relationship between DR and histopathological factor. The inter-observer agreement during the first session varied between 0.30 and 0.63, which improved during the second session toward an agreement between 0.58 and 0.71. Myofibroblast proliferation associated with cancer invasion was found to be the most useful in the diagnosis of DR. In conclusion, the correct detection of myofibroblasts may facilitate the standardization of diagnosis of DR., (© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

Gastric adenocarcinoma of the fundic gland type (GAFG) and pyloric gland adenoma (PGA) have recently been recognized as rare types of neoplasia. We performed comparative immunohistochemical and genetic analyses of 3 GAFGs and 12 PGAs. All of the 3 GAFGs were diffusely positive for pepsinogen-I, MIST1 and MUC6, indicating the predominantly chief cell/mucous neck cell differentiation of these tumors. A small number of H.K-ATPase-positive parietal cells were also scattered. PGAs invariably exhibited diffuse MUC6 and TFF2 expression, consistent with the pyloric gland differentiation of these tumors. Ten of the 12 PGAs also unexpectedly exhibited focal expression of pepsinogen-I and MIST1, suggesting that PGAs often show focal chief cell differentiation and phenotypically resemble mucous neck cells rather than pyloric glands. The mutation analyses revealed activating GNAS mutations, which have been reported to be frequently detected in PGAs, in two of the GAFGs. While GAFGs and PGAs are morphologically distinct lesions, our observations showed their partially overlapping immunohistochemical profiles and shared presence of GNAS mutations, in addition to their common occurrence in the fundic gland mucosa. Based on these observations, we suggest that both GAFGs and PGAs are closely related lesions characterized by a mucous neck cell/chief cell lineage phenotype., (© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

Gastric cancer is one of the most common malignancies worldwide and patients with advanced gastric cancer still have poor clinical outcomes. The overexpression of leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) mRNA in colorectal cancer and its correlation with clinicopathological factors were recently reported by us. In this study, we show LGR5 mRNA overexpression in human gastric cancer specimens by quantitative RT-PCR and in situ hybridization and assess a correlation with clinicopathological factors. The mean expression of LGR5 mRNA in cancerous tissues was five times higher than that in normal tissue (P = 0.0002). Furthermore, LGR5 mRNA expression show marked variation among cases and significantly increased in cases where lymphatic invasion was present compared with those where it was absent (P = 0.0056). Although the mean expression level of LGR5 was observed to be higher in nodal metastasis and venous invasion positive cases compared to negative cases, a significant difference was not observed. These results suggest that LGR5 can be a biomarker for malignancy in gastric cancer., (© 2012 The Authors. Pathology International © 2012 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.)

Neuroendocrine carcinoma (NEC) of the anal canal is exceedingly rare and its histogenesis is poorly understood. We present a case of small-cell NEC of the anal canal in a 70-year-old woman. The NEC appeared as a submucosal tumor at the dentate line and was associated with squamous intraepithelial neoplasia (SIN). The NEC was positive for neuroendocrine markers including synaptophysin, chromogranin A and CD56, whereas the SIN component did not express any of these markers. Both components exhibited p16 overexpression. A PCR analysis revealed that both the SIN and NEC components were positive for human papillomavirus (HPV) 18 DNA. Our observations imply that SIN may be a precursor of anal canal NEC and that HPV18 may play an important role in the histogenesis of anal canal NEC, similar to its role in cervical NEC., (© 2012 The Authors. Pathology International © 2012 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd.)

A case of colloid carcinoma (gelatinous carcinoma) of the intestinal type in the uterine cervix is reported along with the findings of an immunohistochemical study of intracytoplasmic mucus of the neoplastic cells. The patient was a 69-year-old woman with a circumferential uterine cervical tumor measuring about 4 cm. Histopathological examination of the hysterectomy specimen demonstrated typical features of colloid carcinoma. The tumor consisted of numerous mucous nodules, and low-columnar or cuboidal cells with intracytoplasmic mucus lined the margins of the mucous nodules or floated within them. The cytoplasm of neoplastic cells was immunoreactive for both cytokeratins 7 and 20, and the intracytoplasmic mucus was immunoreactive for MUC2 but negative for MUC5AC and MUC6. Nuclei of tumor cells were immunoreactive for CDX2. Colloid carcinoma is a very rare variant of mucus-producing adenocarcinoma of the uterine cervix and probably a heterogeneous group that consists of neoplasms of different histogeneses, that is, neoplasms of endocervical, gastric, and intestinal origins. Results of the immunohistochemical studies in the present case showed that neoplastic cells produced mucus of the large intestine type, thus verifying the presence of a distinct subtype of colloid carcinoma of the cervix that shows the intestinal phenotype.

IgG4-related sclerosing disease is recognized as a distinct clinicopathological entity. It is well known that this disease can occur in the salivary, lacrimal and pituitary glands, in the head and neck region. The nasal cavity is an extremely rare site of involvement of IgG4-related sclerosing disease. Herein is reported a case of multiple IgG4-related sclerosing lesions in the maxillary sinus, parotid gland and nasal septum. A 73-year-old Japanese man presented with nasal obstruction and tumors of the right maxillary sinus and parotid gland were detected, after which resections of these tumors were performed. One year after the last surgery, he noted swelling of the nasal septum, and the tumor was resected. These three tumors had similar histopathology, such as conspicuous fibrosclerotic changes with dense lymphoplasmacytic infiltration and occasional obliterative phlebitis. Immunohistochemistry indicated abundant IgG4-positive plasma cell infiltration and high ratios of IgG4-positive/IgG-positive plasma cells (>70%) in all three lesions. The diagnosis of multiple IgG4-related sclerosing lesions was made. The present case suggests that IgG4-related sclerosing lesion can occur in the maxillary sinus and nasal septum, and represents an extension of the spectrum of IgG4-related sclerosing disease.

IgG4-related sclerosing disease can occur in the cardiovascular system and some inflammatory abdominal aortic aneurysms have been shown to belong to IgG4-related sclerosing disease. Herein is reported a case of IgG4-related inflammatory aortic aneurysm of the aortic arch. A 71-year-old Japanese man was found to have an aneurysm of the aortic arch with maximum dimension of 5.5 cm. The surgically resected aneurysm wall had conspicuous fibrosclerotic changes, dense lymphoplasmacytic infiltration and occasional obliterative phlebitis in the adventitia; the thickness of the adventitia was 6.5 mm. Immunohistochemistry indicated numerous IgG4-positive plasma cell infiltrates; 84% of the IgG-bearing cells were IgG4 positive. The diagnosis of IgG4-related inflammatory aortic aneurysm of the aortic arch was made. Although previously reported IgG4-related inflammatory aortic aneurysms were confined to the abdominal aorta, the present case report demonstrates that IgG4-related inflammatory aortic aneurysm can occur in the aortic arch, thereby extending the spectrum of IgG4-related periaortitis. Further studies are needed to clarify the spectrum of IgG4-related sclerosing disease in the cardiovascular system.

Signet ring cell carcinoma and glassy cell carcinoma are both rare histological subtypes of uterine cervical cancer. This report is of a case of uterine cervical carcinoma arising in a 29-year-old woman who had major components of signet ring cell carcinoma and glassy cell carcinoma within the same tumor. Histochemical and immunohistochemical analyses, including high and low molecular weight cytokeratins, p63 and MUC5AC, additionally demonstrated the squamous and adenocarcinomatous differentiation in the neoplastic cells, which showed otherwise unclassifiable morphology on the haematoxylin-eosin sections. A wide range of differentiation described above supports the speculation that glassy cell carcinoma may arise from the multipotential immature cells that can differentiate into both squamous and glandular cells. It would be precise to classify this tumor as adenosquamous carcinoma. Although adenosquamous carcinoma is not a rare histological subtype in the uterine cervix, it should be necessary to report the presence of glassy cells and signet ring cells when present because the presence of both components is associated with an unfavorable clinical behavior.

We report a case of extraventricular ependymoma arising in a 50-year-old woman that took an aggressive clinical course with recurrence three times. The initial tumor was a well-circumscribed nodule in the right temporal white matter measuring 2 cm in diameter. It showed variegated histological findings mimicking metastatic adenocarcinoma: an epithelioid arrangement of highly pleomorphic cells with pseudopapillary structures and perivascular pseudorosettes, and bizarre multinucleated giant cells with occasional emperiporesis surrounded by abundant mononuclear inflammatory cells, as well as a focal small area of conventional ependymoma. Emperiporesis and abundant mononuclear cell infiltration were not previously described in an ependymoma. The recurrent tumors predominantly showed an epithelioid pattern with frequent formation of astroblastoma-like pseudopapillary structures. Neoplastic cells were markedly atypical and had characteristic intracytoplasmic eosinophilic inclusion bodies. Much of the cells in both the initial and recurrent tumors showed a positive immunostaining for glial fibrillary acidic protein (GFAP) with accentuation to the cytoplasmic processes of the pseudorosettes and pseudopapillary structures. Epithelial membrane antigen (EMA) highlighted the epithelial differentiation of the tumor cells, while cytokeratin was completely negative. Although this tumor might be classified to at least WHO grade III from the histology and aggressive behavior, the exact grading is still controversial because of the rarity of such cases.

Collagenous gastritis, a counterpart of collagenous colitis, is a rare disorder with less than 20 cases reported in the literature. A case of collagenous gastritis in a Japanese woman in her early 20s who had been receiving treatment for atopic dermatitis and bronchial asthma is reported. The patient complained of repeated epigastric pain, and endoscopy revealed multifocal atrophic areas and scars in the gastric body. Biopsy specimens showed a thickened eosinophilic band-like structure with entrapped capillaries approximately 30-70 micro m thick beneath the surface epithelium. It was regarded as a collagen band because it was positive on Azan staining but negative on amyloid staining. This finding was accompanied by marked infiltration of mononuclear cells and eosinophils in the lamina propria; however, no evidence of lymphocytic gastritis was found. Helicobacter pylori infection was not detected and inflammatory cell infiltration was minimal in the mucosa without the collagen band. Immunohistochemical analysis revealed that the band was positive for type III and type VI collagen. The size of the collagen band did not change for 2 years. These findings suggest that subepithelial collagen deposition was due to an abnormal local immune response based on generalized allergic disorder.

Malignant mixed mesodermal tumor is a rare tumor of the ovary and its histogenesis is controversial. We report the case of an ovarian tumor that seemed to be a pure carcinoma and recurred as a carcinosarcoma, and suggest a possible histogenesis for this kind of tumor. The patient was a 62-year-old Japanese woman. The primary tumor was confined to the right ovary and was a histologically poorly differentiated endometrioid adenocarcinoma with focal squamous differentiation. The tumor recurred as peritoneal dissemination 9 months later showing a histological appearance of carcinosarcoma of heterologous type. The recurrent tumor also contained intermingled foci of similar histology as the primary tumor. The carcinomatous component of the recurrent tumor showed more obvious differentiation to adenocarcinoma with increased expression of epithelial markers compared to the primary tumor. Epithelial membrane antigen was positive also in a few cells of the sarcomatous component, which implies that this tumor had features of metaplastic carcinoma. The DNA ploidy pattern of the primary ovarian tumor was diploid, while an additional aneuploid subpopulation appeared in the recurrent tumor. These findings suggest the possible histogenesis of carcinosarcoma of the ovary as progression and clonal evolution of endometrioid adenocarcinoma.