Comprehensive immunohistochemical analysis of the gastrointestinal and Müllerian phenotypes of 139 ovarian mucinous cystadenomas.

Mucinous cystadenoma is one of the most common benign ovarian neoplasms. The immunophenotypes and histogenetic relationships of mucinous cystadenomas with a Müllerian-type epithelium have not been fully explored. We elucidated the direction of differentiation of the mucinous epithelium that constitutes mucinous cystadenomas. Special attention was paid to the existence of gastrointestinal (GI)-type mucinous epithelium, and its association with background Müllerian-type epithelium. Immunohistochemistry was performed in 139 cases of mucinous cystadenoma to evaluate the expression of Claudin-18 (CLDN18), a novel marker of gastric differentiation; CDX2, a marker of intestinal differentiation; and estrogen receptor (ER), a marker of Müllerian differentiation. We found that GI differentiation characterized by CLDN18 and/or CDX2 positivity was observed in mucinous epithelium of most mucinous cystadenomas (129/139 cases, 93%). In a subset of these cases, the tumor was composed of mucinous epithelium exhibiting an intermediate GI and Müllerian phenotype (CLDN18+/CDX2±/ER+). Of note, in 12 cases, a transition from background Müllerian-type epithelium to mucinous epithelium with GI differentiation was identified. A minor subset (6%) of mucinous cystadenomas was considered a pure Müllerian type because the epithelium exhibited a CLDN18-/CDX2-/ER + immunophenotype. In conclusion, mucinous cystadenomas consist of three major subtypes: GI, Müllerian, and intermediate types. Most mucinous cystadenomas are GI-type, and they should be considered a precursor of GI-type mucinous borderline tumors. The existence of intermediate-type mucinous cystadenomas, and areas of transition from Müllerian-type to GI-type epithelium suggest that GI-type mucinous epithelium can arise from Müllerian duct derivatives or surface epithelium exhibiting Müllerian metaplasia in the ovary.

The fibrous tapetum of the horse eye.

The tapetum lucidum is a light-reflective tissue in the eyes of many animals. Many ungulates have a fibrous tapetum. The horse has one of the largest eyes of any living animal and also has excellent vision in low-light environments. This study aimed to clarify the macroscopic tapetal shape, relationship between the tapetal thickness and the degree of pigmentation of the retinal pigment epithelium (RPE), spatial relationship between the visual streak and the tapetum, and wavelength of the light reflected from the tapetum in the horse. Macroscopically, weak light revealed the tapetum as a horizontal band located dorsal to and away from the optic disc. The tapetum expanded dorsally as the illumination increased. The tapetal tissue consisted of lamellae of collagen fibrils running parallel to the retinal surface; these spread over almost the entire ocular fundus and were thicker in the horizontal band dorsal to the disc. Only the horizontal band of the tapetum was covered by unpigmented RPE, suggesting that this band reflects light and is responsible for mesopic and scotopic vision. The visual streak was located in the ventral part of the horizontal band, ventral to the thickest part of the tapetum. The wavelength of the light reflected from the horizontal band of the tapetum was estimated from the diameter and interfibrous distance of the collagen fibrils to be approximately 468 nm. Therefore, the light reflected from the tapetum should be more effectively absorbed by rods than by cones, and should not interfere with photopic vision.

Formation of excess sublobules in the cerebellum of hypothyroid rats.

Cerebellar folia may increase in number in hypothyroid rats (Lauder et al., 1974; Hasebe et al., 2008a). In this study, we aimed to confirm the formation of an excess sublobule and to determine whether excess sublobules are consistently formed in conserved positions in hypothyroid rats. Instead of the foliation pattern partitioned by cerebellar fissures, we employed the bifurcation pattern of the internal granular layer for investigation of complexity of the cerebellar cortex in hypothyroid rats. The basic foliation pattern of the cerebellum was intact in hypothyroid rats, but lobules III to IX frequently showed an increase in the number of sublobules. The excess sublobules were mainly found in the folia and along the shallow region of the fissure. In other words, the excess sublobules were not located in random locations but rather in specific locations. The area in the internal granular layer of lobules V to IX was significantly larger than that in control rats. From the increased area of the internal granular layer it may be inferred that internal granular cells increase in number than those in normal rats. In our study, regions within the cerebellum that show an excess of sublobules correlate with regions that show an intermediate to late-forming internal granular layer (Altman, 1969). Our observations fit with the view that excess sublobules are formed by the external granular layer showing prolonged cell proliferation and hypothyroidism predominantly has an adverse impact on the intermediate to late phases in development of the internal granular layer.

SOX9 expression and its methylation status in gastric cancer.

SOX9 is a member of the SOX [Sry-related high-mobility group (HMG) box] family and is required for the development and differentiation of multiple cell lineages. To clarify the significance of SOX9 in gastric carcinoma (GC), immunohistochemical expression of SOX9 and the CpG island methylation status of SOX9 were evaluated and compared with clinicopathological factors including overall survival. SOX9 expression was immunohistochemically evaluated in 382 GC tumors and the methylation status was examined in 121 GC tumors. SOX9 expression and its methylation status in six GC cell lines, their Epstein-Barr virus (EBV)-infected cell lines, and two EBV-associated GC cell lines was also examined. The SOX9 expression increased from non-neoplastic mucosa to early cancer. High expression of SOX9 was seen in 212 cases (56%). SOX9 expression was inversely related to advanced tumor stage, vessel infiltration, nodal metastasis, and EBV infection. Fifty-eight (48%) of 121 GC tumors had a methylated promoter in GC and the methylated status was related to low expression. The expression and methylation status were not related to prognosis. Three of six cell lines had increased methylation through EBV infection and decreased SOX9 expression. Upregulation of SOX9 is related to GC development. Downregulation by promoter methylation is related to GC progression and EBV infection. SOX9 is closely related to GC carcinogenesis and EBV-associated GC carcinogenesis.

Laterality of spinocerebellar neurons in the chicken spinal cord.

The aim in this study is to elucidate the laterality of chicken spinocerebellar (SC) neurons that originate from the caudal cervical to caudal lumbosacral spinal cord. SC neurons in the spinal segment (SS) 17-20 consisted of a mixture of crossed and uncrossed axons. SC neurons in the more cranial and caudal SS than SS 17-20 (transitional zone) were generally uncrossed and crossed, respectively. In the transitional zone, SC neurons in spinal border cells and ventral border cells of the ventral horn changed dramatically from an uncrossed to a crossed type between SS 17 and SS 18. Chicken SC neurons are markedly different in laterality from mammalian SC neurons.

Composite diffuse large B-cell lymphoma and CD20-positive peripheral T-cell lymphoma.

Composite lymphoma is defined as two or more distinct types of lymphoma in a single anatomical site. Among various combinations, composite B-cell and T-cell non-Hodgkin's lymphomas (CBTL) are very infrequent. Herein we describe a 66-year-old female with CBTL presenting with lymphadenopathy, multiple bone lesions and an epidural tumor. Light microscopic examination of a biopsied cervical node revealed a dual population of lymphoid cells: sheets of large cells admixed with medium-sized cells. The large cells expressed B-cell markers and showed immunoglobulin light chain restriction, consistent with diffuse large B-cell lymphoma (DLBCL). The medium-sized cells were positive for CD20 as well as T-cell markers. Because polymerase chain reaction amplification showed monoclonal rearrangement of the T-cell receptor ß chain gene, this population was compatible with peripheral T-cell lymphoma not otherwise specified (PTCL-NOS). We therefore made a diagnosis of composite DLBCL and CD20-positive PTCL-NOS. Complete remission was achieved after six cycles of R-CHOP regimen (rituximab, doxorubicin, vincristine, cyclophosphamide and prednisolone). This is the first report of CD20-positive PTCL-NOS associated with composite lymphoma. Moreover, a literature review of composite DLBCL and PTCL-NOS indicates that this rare clinical entity may be featured by efficacy of systemic chemotherapy in spite of prevalent extranodal lesions.

Hyperbilirubinemia after hematopoietic stem cell transplantation: comparison of clinical and pathologic findings in 41 autopsied cases.

Hyperbilirubinemia is often associated with morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Diagnosis of its etiology is usually made clinically among various possible causes, and analysis of histological findings as compared with the clinical diagnosis has not been performed sufficiently. We retrospectively analyzed clinical and pathological findings in 41 autopsied patients who died with hyperbilirubinemia (>2 mg/dL). Overall, liver graft-versus-host disease (GVHD) showed the most prominent discordance between clinical and pathological diagnoses. Only 11 of the 22 patients, considered to have liver GVHD clinically, had GVHD findings at autopsy. Serum gamma-glutamyl transpeptidase (GGT), GGT/aspartate aminotransferase (AST) ratio, and alkaline phosphatase (ALP)/AST ratio in GVHD patients were significantly higher compared with those without GVHD (p = 0.02, <0.01, and 0.03, respectively), which was useful in clinical diagnosis of liver GVHD. Other major findings include liver invasion of the primary malignancies in 8 patients, post-transplant lymphoproliferative disorder of the liver in two patients, and disseminated liver invasion by fungus or varicella-zoster virus in one patient, respectively. Although analysis of clinical data is useful for narrowing diagnosis, histological analysis by liver biopsy is crucially important, especially in cases suspected of having GVHD.

Claudin-18 is an early-stage marker of pancreatic carcinogenesis.

Pancreatic ductal neoplasms exhibit gastric epithelium-like characteristics. In this study, we evaluated the expression of claudin-18 (CLDN18), a gastric epithelium-associated claudin, in pancreatic intraepithelial neoplasias (PanINs), intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs), and pancreatic ductal adenocarcinomas (PDACs) using immunohistochemistry. We observed a high level of expression of CLDN18 in PanINs (31/32, 97%), IPMNs (61/65, 95%), and MCNs (4/5, 80%) using ordinary tissue section analysis. Furthermore, we observed a high level of CLDN18 expression in PDACs (109/156, 70%) using tissue microarray analysis. However, the normal pancreatic duct or the ductal metaplasia of the acinar cells was not immunoreactive. Comparative analysis of CLDN18 and phenotypic markers in IPMNs revealed that simultaneous expression of CLDN18 and intestinal markers frequently occurred, even in intestinal-type IPMNs. CLDN18 variant 2 mRNA was expressed and was similarly upregulated by phorbol 12-myristate 13-acetate (PMA) treatment in pancreatic cancer cell lines and in a gastric cancer cell line. An inhibitor of pan-PKC (GF109203X) completely suppressed this upregulation in pancreatic cancer cells. These results indicate that CLDN18, a marker for the early carcinogenetic process, is commonly expressed in precursor lesions of PDAC. Activation of the PKC pathway might be involved in CLDN18 expression associated with pancreatic carcinogenesis.

Claudin-18 in biliary neoplasms. Its significance in the classification of intrahepatic cholangiocarcinoma.

Claudin-18 (CLDN18), a tight junction protein specific to stomach and lung, is aberrantly expressed in preinvasive and invasive neoplasms of the pancreas. To investigate the significance of CLDN18 expression in biliary neoplasms, immunohistochemical analysis was performed. CLDN18 expression was frequently observed in the epithelial cells of extrahepatic bile duct carcinomas (90%, n = 99), intrahepatic intraductal papillary neoplasms of the bile duct (IPNBs, 100%, n = 11), and extrahepatic IPNBs (89%, n = 9), while it was less frequent in intrahepatic cholangiocarcinomas (ICCs, 43%, n = 83). Interestingly, CLDN18 expression was also frequently observed in precancerous lesions such as biliary intraepithelial neoplasias (78%, n = 18). Among ICCs, CLDN18-positive cases showed higher frequencies of periductal infiltrative growth, perineural invasion, and lymph node metastasis. Multivariable analysis demonstrated that positive CLDN18 expression was an independent risk factor for lymph node metastasis in ICCs. Furthermore, CLDN18 expression was associated with poor overall survival by univariable analysis, as well as lymph node metastasis. These results suggest that CLDN18 may play an important role in biliary carcinogenesis, and especially in ICCs, it is associated with aggressive behavior and serves as a useful marker for the classification of ICC.

Transcriptional factor typing with SOX2, HNF4aP1, and CDX2 closely relates to tumor invasion and Epstein-Barr virus status in gastric cancer.

BACKGROUND: Gastric cancer (GC) is a major cancer, sometimes associated with Epstein-Barr virus (EBV). Some transcriptional factors (TFs) are specific to the digestive tract and related to the character of the tumors. METHODS: We studied three TFs, SOX2, CDX2, and hepatocyte nuclear factor 4 alpha-promoter 1 (HNF4aP1) in GC. First, 255 tumors including 31 EBV-associated GC were immunohistochemically examined using tissue arrays and compared TF type and mucin phenotype. We classified them into 4 TF types: N-TF type as SOX2-/HNF4aP1- tumor, G: SOX2+/HNF4aP1-, GI: SOX2+/HNF4aP1+, and I: SOX2-/HNF4aP1+. Next, 915 GCs were intensely investigated and compared with their clinicopathological factors. RESULTS: In the first study, 255 GCs were classified into N-TF 44%, G-TF 31%, GI-TF 3%, and I-TF 2%. The TF type did not strictly accord with the mucin phenotype, classified by MUC2/5AC/6/CD10 expression. EBV status was the only factor related to both the TF and mucin phenotype classifications (P<0.0001, <0.0001). TF classification is related to more factors including tumor stage, than mucin phenotype classification. The second study using 915 GCs revealed that N-TF gradually increased and I-TF decreased as GC invaded deeper. TF classification was not related to nodal involvement in each tumor stage. HNF4aP1 and CDX2 were independent factors for early stage tumor in logistic regression analysis. CONCLUSIONS: EBV-associated GC is a discriminating group in both TF and mucin phenotype. TF classification, especially the absence of HNF4aP1 and CDX2, is related to tumor invasion. TF classification is a useful marker to study the carcinogenesis of GC further.

Trajectories in the spinal cord and the mediolateral spread in the cerebellar cortex of spinocerebellar fibers from the unilateral lumbosacral enlargement in the chicken.

Spinocerebellar (SC) neurons in the lumbosacral enlargement (LSE) give rise mainly to crossed fibers and generally terminate in parasagittal bands in the granular layer of the chicken cerebellar cortex. However, parasagittal bands for mossy fiber terminals have not always been clear in some cerebellar folia. The present study aimed at (1) observing the course in the spinal cord of the spinocerebellar tracts (SCTs), (2) confirming whether SC fibers originating from the unilateral LSE terminate in parasagittal bands, and (3) elucidating the relationship between the ventral and lateral funicular parts of the SCTs in the cervical enlargement (CE) using anterograde and retrograde labeling methods. The SCTs were located in the medial part of the ventral funiculi in spinal segment (SS) 27, the full width of the ventral funiculi in SS 22, the lateral and ventral funiculi in SS 14 and in the lateral funiculi from SS 10 rostralward. Projection areas in the cerebellar cortex of SC fibers were studied following unilateral injections of WGA-HRP into the LSE. As a result, SC fibers from the LSE terminated bilaterally in parasagittal bands of folia II-VI and IXc. Labeled terminals in the injected side were similar in number to those in the other side in folia II-IV and IXc and more than those in the other side in folia V and VI. Following ablation of the left (contralateral) lateral funiculus of the CE, the same tracer was injected into the right (ipsilateral) LSE or into the anterior or posterior cerebellar lobe. As a result, anterogradely labeled SC fibers passing through the ventral funiculus in the CE mainly terminated in the contralateral cerebellar cortex in folia II, III and IV, and in the ipsilateral cerebellar cortex in folia V, VI and IX. Following ablation of the unilateral lateral funiculus, retrogradely labeled neurons in the contralateral LSE were found in all SC neuron groups showing marked reduction in number. Thus, the ventral and lateral funicular parts of the SCTs in the CE were not pathways for specific SC neuron groups but different in projection areas.

Spinocerebellar projections from the cervical and lumbosacral enlargements in the chicken spinal cord.

In birds, spinocerebellar (SC) projections to the cerebellar cortex have not been understood well. We examined SC fiber terminal fields originating from the cervical and lumbosacral enlargements (CE and LSE, respectively) in the chicken. SC fiber terminals show parasagittal bands in the granular layer. Labeled terminals from the CE were distributed primarily in folia II-V and IX. Parasagittal bands of labeled terminals from the CE were not clearly separated in folia II and III but were clearly separated in folia IV and V. In folium IX, labeled terminals were diffusely distributed in all subfolia with no evidence of banding. The numbers of bands were 5 in folium II, 12 in folium III and 7 in folia IV and V at maximum. Labeled terminals from the LSE were distributed primarily in folia II-VI and IX. Labeled terminals from the LSE were arranged in 4 bands in folium II and in 8 bands in folium III at maximum. Parasagittal bands from the LSE in folia IV and V were not clearly separated. In folium VI, the numbers of parasagittal bands was 6 at maximum. In folium IX, labeled terminals were mainly found in subfolium IXc forming 6-8 parasagittal bands. There were more parasagittal bands of labeled terminals from the CE than from the LSE. The topography of SC fiber terminals from the CE was different from that of SC fiber terminals from the LSE.

Expression of ribonucleotide reductase M2 subunit in gastric cancer and effects of RRM2 inhibition in vitro.

Ribonucleotide reductase M2 subunit is one of two subunits that constitute ribonucleotide reductase, the enzyme that catalyzes the conversion of ribonucleotide 5'-diphosphates into 2'-deoxyribonucleotides, which are required for DNA synthesis. This study was conducted to investigate the roles of ribonucleotide reductase M2 subunit in gastric cancer. The expression of ribonucleotide reductase M2 subunit protein was examined by immunohistochemistry. In normal gastric mucosa, ribonucleotide reductase M2 subunit expression was restricted to the neck regions of gastric pits and no expression was observed in the surface epithelium. Among 112 gastric cancer tissues, ribonucleotide reductase M2 subunit overexpression (≥10% cancer cells stained) was observed in 72 cases (64.3%). Ribonucleotide reductase M2 subunit overexpression was significantly associated with male sex (P = .015), presence of muscularis propria invasion (P = .020), presence of Epstein-Barr virus (P = .045), expression of survivin (P = .0014), and DNA methyltransferase 1 (P = .043), but not with age, histology, tumor size, lymph node metastasis or expression of phosphatase and tensin homolog, phosphorylated signal transducer, and activator of transcription 3 or p53. Suppression of ribonucleotide reductase M2 subunit synthesis, using small interfering RNA, inhibited the growth of 3 gastric cancer cell lines, MKN-1, MKN-7, and SNU-719. Our data suggest that ribonucleotide reductase M2 subunit overexpression could be associated with the gastric cancer progression and that suppression of its function is a potential therapeutic strategy in gastric cancer.

Distribution of astroglial lineage cells in developing chicken telencephalon from embryo to young chick.

The largest area of the avian telencephalon (Tc) is the subpallium [basal ganglia (BG)], and the pallium (cortex) is a narrow area located at the surface of the Tc. However, recent studies have proposed that most of the area of the avian Tc is the pallium, which corresponds to the cerebral cortex of mammals. This theory is based on neuronal elements with little regard to glial cells, which play important roles in neurogenesis. In the present study, we observed the distribution of glial cells using immunohistochemistry during maturation and discuss the division of the Tc by glial elements. In the early stage, the distribution and morphology of vimentin-positive radial glial cells were different between dorsal and ventral areas when they began to spread their processes toward the pia matter. During the development stage, vimentin-positive long processes divide the pallium and BG by the lamina pallio-subpallialis. Moreover, the pallium was divided into four regions by vimentin and glial fibrillary acidic protein-positive elements in the later stage.

Gastric carcinoma with osteoclast-like giant cells. Lymphoepithelioma-like carcinoma with Epstein-Barr virus infection is the predominant type.

Osteoclast-like giant cells (OGC) are rare in gastric carcinomas. Histopathological study of seven gastric carcinomas with OGC demonstrated three distinct types: lymphoepithelioma-like carcinoma (LELC), non-LELC, and giant cell tumor (GCT) types. LELC is a poorly differentiated adenocarcinoma with prominent lymphoid stroma. The LELC type (n = 4) showed similar histology to LELC of the stomach, except that they were accompanied by OGC and granulomatous reaction. Epstein-Barr virus (EBV) infection was demonstrated by EBV-encoded RNA (EBER) in situ hybridization (ISH) in all the neoplastic cells. The non-LELC type (n = 2) consisted of EBV-negative carcinoma cells with inflammatory infiltrates. OGC and granulomas were frequently observed in the glandular lumens with accumulated mucus. The GCT type (n = 1) was a neuroendocrine carcinoma, containing many OGC with metaplastic bone formation, which showed typical morphological features of OGC in GCT of the bone. In all three types, OGC expressed CD68, but not cytokeratin, indicating that OGC had a reactive histiocytic lineage. Both LELC and non-LELC types are included in the differential diagnosis of isolated granulomatous gastritis, and EBER-ISH was useful for the identification of LELC type. Both LELC and no-LELC types were also suggested to have better prognoses, but the behavior of the GCT type needs to be further characterized.

Downregulation of microRNA-200 in EBV-associated gastric carcinoma.

EBV-associated gastric carcinoma is a distinct gastric carcinoma subtype with characteristic morphologic features similar to those of cells that undergo epithelial-to-mesenchymal transition. The effect of microRNA abnormalities in carcinogenesis was investigated by measuring the expression of the epithelial-to-mesenchymal transition-related microRNAs, miR-200a and miR-200b, in 36 surgically resected gastric carcinomas using quantitative reverse transcription-PCR analysis. MiR-200 family expression was decreased in EBV-associated gastric carcinoma, as compared with that in EBV-negative carcinoma. Downregulation of the miR-200 family was found in gastric carcinoma cell lines infected with recombinant EBV (MKN74-EBV, MKN7-EBV, and NUGC3-EBV), accompanied by the loss of cell adhesion, reduction of E-cadherin expression, and upregulation of ZEB1 and ZEB2. E-cadherin expression was partially restored by transfection of EBV-infected cells with miR-200 family precursors. Reverse transcription-PCR analysis of primary precursors of miR-200 (pri-miR-200) revealed that the transcription of pri-miR-200 was decreased in EBV-infected cells. Transfection of MKN74 cells with BARF0, EBNA1, and LMP2A resulted in a decrease of pri-miR-200, whereas transfection with EBV-encoded small RNA (EBER) did not. These four latent genes contributed to the downregulation of the mature miR-200 family and the subsequent upregulation of ZEB1/ZEB2, resulting in the reduction of E-cadherin expression. These findings indicate that all the latency type I genes have a synergetic effect on the downregulation of the miR-200 family that leads to reduced E-cadherin expression, which is a crucial step in the carcinogenesis of EBV-associated gastric carcinoma.

Topography of ganglion cells and photoreceptors in the sheep retina.

Retinal topographies of some cell types and distribution of the tapetum lucidum in the sheep's eye were investigated in this study. The tapetum was observed macroscopically in the fundus. The topographical distributions of retinal ganglion cells (RGCs), cones, and rods were simultaneously analyzed in retinal whole mounts stained with cresyl violet. Short-wavelength-sensitive (S) cones were immunocytochemically identified in retinal whole mounts. The tapetum was located dorsal to the optic disc, with the nasal part elongated horizontally and the temporal part expanded dorsally. RGCs were distributed densely in the area centralis, horizontal visual streak, and anakatabatic area. The highest density in the area centralis was approximately 18,000 RGCs/mm(2). Cones showed high density in the horizontal area crossing the optic disc and dorsotemporal area, whereas rods showed high density in the horizontal area, which was greater in height than the horizontal area of high cone density. S cones showed high density in the dorsotemporal retina. The rod/cone ratios were high horizontally in the dorsal retina to the optic disc, with a mean value of 11:1. The cone/RGC and rod/RGC ratios were lower in the horizontal and dorsotemporal retina, and the rod/cone/RGC ratio was lowest in the area centralis (9:1:1). The retinal topographies and distribution of the tapetum were specialized in the horizontal and dorsotemporal fundus. This suggests that sheep have better visual acuity in horizontal and anteroinferior visual fields and that this specialization is related to the visual ecology of sheep.

SALL4 represents fetal gut differentiation of gastric cancer, and is diagnostically useful in distinguishing hepatoid gastric carcinoma from hepatocellular carcinoma.

The novel stem cell marker SALL4 has been identified as a diagnostic marker of germ cell tumors, especially yolk sac tumors, in gonadal organs. To clarify the significance of SALL4 as an oncofetal protein, we investigated SALL4 expression by immunohistochemistry in non-neoplastic stomach and gastric carcinoma with particular emphasis on á-fetoprotein (AFP)-producing gastric carcinoma, as AFP-producing gastric carcinoma shares expression of AFP and glypican 3 (GPC3) with yolk sac tumors and hepatic neoplasms. A total of 338 gastric carcinomas, 60 hepatocellular carcinomas, and 48 cholangiocellular carcinomas were studied by immunohistochemistry on tissue microarrays. In addition, more detailed whole tissue section immunohistochemistry was performed on non-neoplastic gastric tissue from 5 adult and 8 fetal specimens, 6 hepatoblastomas, and 31 cases of AFP-producing gastric carcinomas. SALL4 expression was observed in the neofetal stomach in gestational week 9 and disappeared thereafter. It was also identified by tissue microarray study in a fraction of gastric carcinomas (51 of 338, 15%), associated with older age (P=0.0001), male sex (P=0.0033), intestinal-type histology (P=0.0001), and synchronous liver metastasis (P=0.0047). AFP and GPC3 were closely associated with SALL4 expression in gastric carcinoma (both, P<0.0001), and a full-section study indicated that SALL4 was positive in all 31 cases of AFP-producing gastric carcinoma with diffuse staining in 24 cases (78%). Diffuse SALL4 expression was observed in the histologic patterns of hepatoid (89%), glandular (57%), and clear cell (39%) AFP-producing gastric carcinoma. In addition, SALL4 expression was completely negative in hepatoblastoma (n=6) and hepatocellular carcinoma (n=60). SALL4 is an oncofetal protein similar to AFP and GPC3, but it represents fetal gut differentiation in gastric carcinoma. SALL4 is a sensitive marker for AFP-producing gastric carcinoma and is especially useful to distinguish hepatoid gastric carcinoma from hepatocellular carcinoma.

Relationship between distribution of tapetum fibrosum and retinal pigment epithelium in the sheep eye.

The tapetum lucidum is a light-reflective device improving visual sensitivity in mesopic vision. There have been few studies on tapetal distribution and its relationship with degree of pigmentation in the retinal pigment epithelium (RPE). In the present study, sheep's eyes were used for macroscopical observation of the tapetum, and then histological sections of the posterior eyecups were made to analyze the distribution of tapetal thickness and degree of pigmentation in the RPE. Macroscopically, with available light, the tapetum was located in the dorsal eye fundus to the optic disc and showed an L-shape with the horizontally elongated nasal part and the dorsally expanded temporal part. In photographs with a flash, the tapetal area expanded and showed a more triangular shape. The tapetum histologically consisted of layers of dense collagen fibers and was thicker in the temporal part than in the nasal part. The maximum tapetal thickness was approximately 70 microm. The histological tapetal area was similar to the tapetal shape with a flash light. The pigmentation of the RPE was divided into three types, nonpigmented, transitional, and pigmented areas. The nonpigmented area was similar to the tapetal shape with available light. It is suggested that approximately 55% of the histological tapetal area is covered with the nonpigmented area and is functional under a natural light condition. The functional tapetal area was similar to the L-shaped high-density area of retinal ganglion cells.

Prominent Mott cell proliferation in Epstein-Barr virus-associated gastric carcinoma.

The proliferation of Mott cells (plasma cells with multiple Russell bodies) is rarely observed in nonhematopoietic tumors, and no reports of this phenomenon in malignant epithelial neoplasms have been published. We present 2 cases of gastric carcinoma associated with prominent Mott cell proliferation. Histologically, both tumors consisted of extensive lymphoplasmacytic infiltration and numerous Mott cells with dysplastic epithelial cells. The epithelial cells showed overt cytologic atypia; infiltrating cells did not show cytologic atypia, immunoglobulin light chain restriction, or clonal immunoglobulin gene rearrangement. In situ hybridization for Epstein-Barr virus (EBV)-encoded small RNA (EBER) labeled the carcinoma cells but not the lymphoplasmacytic cells. The Mott cell accumulation was a reactive phenomenon in gastric carcinoma associated with EBV. The differential diagnosis included primary gastric lymphoma and nonneoplastic conditions such as Russell body gastritis; EBER in situ hybridization was helpful in their differentiation.