Next generation sequencing targeted detection of somatic mutations in patients with mucinous adenocarcinoma of the appendix.

The aim of this study was to investigate the mutations in mucinous adenocarcinoma of the appendix (MAA). SNV was detected in 15 patients with MAA, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and reactome pathway analyses were performed. Tumor mutational burden (TMB), mutant-allele tumor heterogeneity (MATH), microsatellite instability (MSI) was analysis. Finally, the human leukocyte antigen (HLA) typing of the samples was detected. The results showed that TP53 (27 %) and KRAS (20 %) were the highest mutation frequency in the sample, mainly occur in p53 pathway and RTK-RAS pathway. GO analysis reveals mutated genes are closely related to the regulation of GTPase activity, regulation of small GTPase mediated signal transduction and other BP, related to the CC and MF. Analysis of KEGG pathways indicated that the top canonical pathways associated with SNV was Wnt signaling pathway. Reactome pathway analysis further revealed that the mutant genes were closely related to muscle contraction. Only one patient had moderate TMB level and one patient with high MSI. In conclusion, the most common mutated genes and the signaling pathways closely related to MAA development were detected in this study, which will contribute to the development of immunotherapy for patients with MAA.

The Frontiers of Appendiceal Controversies: Mucinous Neoplasms and Pseudomyxoma Peritonei.

Appendiceal mucinous neoplasms show a range of morphologic features and biological risk. At one end of the spectrum, high-grade adenocarcinomas are cytologically malignant with infiltrative invasion, lymph node metastases, and behavior similar to that of extra-appendiceal mucinous adenocarcinomas. At the other end, mucinous neoplasms confined to the mucosa are uniformly benign. Some cases lying between these extremes have potential risk to metastasize within the abdomen despite a lack of malignant histologic features. They show "diverticulum-like," pushing invasion of mostly low-grade epithelium through the appendix with, or without, concomitant organizing intra-abdominal mucin. The latter condition, widely termed "pseudomyxoma peritonei," tends to pursue a relentless course punctuated by multiple recurrences despite cytoreductive therapy, culminating in death for many patients. The combination of bland histologic features and protracted behavior of peritoneal disease has led some authors to question whether these metastatic tumors even represent malignancies. The World Health Organization and its cadre of experts widely promote usage of "low-grade appendiceal mucinous neoplasm" as an umbrella term to encompass benign and malignant conditions, as well as those that have uncertain biological potential. Although this practice greatly simplifies tumor classification, it causes confusion and consternation among pathologists, clinical colleagues, and patients. It also increases the likelihood that at least some patients will undergo unnecessary surveillance for, and treatment of, benign neoplasms and non-neoplastic conditions. The purpose of this review is to critically evaluate the relevant literature and discuss a practical approach to classifying appendiceal mucinous neoplasms that more closely approximates their biological risk.

Epigenetic inactivation of the autophagy-lysosomal system in appendix in Parkinson's disease.

The gastrointestinal tract may be a site of origin for α-synuclein pathology in idiopathic Parkinson's disease (PD). Disruption of the autophagy-lysosome pathway (ALP) may contribute to α-synuclein aggregation. Here we examined epigenetic alterations in the ALP in the appendix by deep sequencing DNA methylation at 521 ALP genes. We identified aberrant methylation at 928 cytosines affecting 326 ALP genes in the appendix of individuals with PD and widespread hypermethylation that is also seen in the brain of individuals with PD. In mice, we find that DNA methylation changes at ALP genes induced by chronic gut inflammation are greatly exacerbated by α-synuclein pathology. DNA methylation changes at ALP genes induced by synucleinopathy are associated with the ALP abnormalities observed in the appendix of individuals with PD specifically involving lysosomal genes. Our work identifies epigenetic dysregulation of the ALP which may suggest a potential mechanism for accumulation of α-synuclein pathology in idiopathic PD.

Identification of podocalyxin-like protein as a high endothelial venule ligand for L-selectin: parallels to CD34.

The leukocyte adhesion molecule, L-selectin, mediates the recruitment of lymphocytes to secondary lymphoid organs via interactions with specific ligands presented on high endothelial venules (HEV). Although the HEV-derived ligands for L-selectin are still incompletely defined, they share a common sialomucin-like structure which is thought to present clustered oligosaccharides to the lectin domain of L-selectin. Podocalyxin-like protein (PCLP) is a transmembrane sialomucin that is similar in structure to the well-characterized L-selectin ligand CD34. PCLP has been shown previously to be expressed on the foot processes of podocytes in the kidney glomerulus as well as on vascular endothelium at some sites. We have determined that PCLP is present on HEV, where it binds to both recombinant L-selectin and the HEV-specific monoclonal antibody MECA-79. Furthermore, purified HEV-derived PCLP is able to support the tethering and rolling of lymphocytes under physiological flow conditions in vitro. These results suggest a novel function for PCLP as an adhesion molecule and allow the definition of conserved structural features in PCLP and CD34, which may be important for L-selectin ligand function.

A comprehensive study of nondysplastic and dysplastic serrated polyps of the vermiform appendix.

Serrated colorectal polyps often show DNA hypermethylation and/or BRAF mutations and have been implicated in the "serrated neoplastic pathway." Although similar lesions occur in the appendix, they have never been systematically investigated. We evaluated a study group of 56 serrated polyps, a control group of 17 mucinous cystadenomas, and 4 adenocarcinomas with adjacent serrated polyps of the appendix to better understand their pathogenesis. The study cases were classified as nondysplastic or dysplastic serrated polyps and evaluated for MLH-1, MSH-2, MGMT, beta-catenin, p53, and Ki-67 expression, BRAF and KRAS mutations, and microsatellite instability. Serrated polyps usually occurred in older adults with no sex predilection. Most (59%) lacked dysplasia, but all showed similar molecular features, regardless of the degree of dysplasia present. Decreased MLH-1 (50%, P<0.001) and/or MGMT (59%, P<0.001) expression and BRAF (29%, P=0.007) mutations were significantly more common in serrated polyps, but BRAF mutations were detected in a minority of the extracted DNA in 15/16 cases. Of the 28 cases with decreased MLH-1 expression, none showed high-frequency microsatellite instability. Loss of MLH-1 (25%) or MGMT (50%) expression and BRAF or KRAS mutations (50%) were inconsistently present in adenocarcinomas and were not identified in combination in any cases. We conclude that molecular features of the "serrated neoplastic pathway" are present with similar frequencies among dysplastic and nondysplastic serrated appendiceal polyps and are not highly prevalent in adjacent carcinomas. These features, including BRAF mutations, may be more closely related to a serrated morphology in appendiceal polyps rather than biologically important changes.

Peripheral lymphoid tissue-like adhesion molecule expression in nodular infiltrates in inflammatory myopathies.

Non-granulomatous nodular accumulations of inflammatory cells in inflammatory myopathies were studied to characterize adhesion mechanisms used for leukocyte recruitment. The nodules had a B-cell-rich center surrounded by a helper T-cell-rich peripheral zone, resembling lymph nodes. The T-cell-rich zones harbored high-walled venules resembling high endothelial venules (HEV), whose endothelia frequently expressed ICAM-1, VCAM-1, and less constantly E-selectin. This endothelial adhesion molecule profile differs from that found in polymyositis, inclusion body myositis, or dermatomyositis, but resembles that in lymphoid tissues. Also, the peripheral lymph node addressin, a vascular addressin specific for peripheral lymphoid tissue HEV, was present on many HEV. This adhesion system is probably responsible for the excessive lymphocyte recruitment. The similar cellular organization and lymphocyte recirculation mechanisms of the nodular infiltrates in muscle and of lymph nodes suggest that the former may also produce antibodies.

Assessment of the prevalence of vCJD through testing tonsils and appendices for abnormal prion protein.

The objective of this study was to determine the age group or groups which will provide the most information on the potential size of the vCJD epidemic in Great Britain via the sampling of tonsil and appendix material to detect the presence of abnormal prion protein (PrP(Sc)). A subsidiary aim was to determine the degree to which such an anonymous age-stratified testing programme will reduce current uncertainties in the size of the epidemic in future years. A cohort- and time-stratified model was used to generate epidemic scenarios consistent with the observed vCJD case incidence. These scenarios, together with data on the age distribution of tonsillectomies and appendectomies, were used to evaluate the optimal age group and calendar time for undertaking testing and to calculate the range of epidemic sizes consistent with different outcomes. The analyses suggested that the optimal five-year age group to test is 25-29 years, although a random sample of appendix tissue from all age groups is nearly as informative. A random sample of tonsil tissue from all age groups is less informative, but the information content is improved if sampling is restricted to tissues removed from those over ten years of age. Based on the assumption that the test is able to detect infection in the last 75% of the incubation period, zero detected infections in an initial random sample of 1000 tissues would suggest that the epidemic will be less than 870,000 cases. If infections are detected, then the model prediction suggests that both relatively small epidemics (800+ cases if one is detected or 8300+ if two are detected) and larger epidemics (21,000+ cases if three or more are detected) are possible. It was concluded that testing will be most informative if undertaken using appendix tissues or tonsil tissues removed from those over ten years of age. Large epidemics can only be excluded if a small number of infections are detected and the test is able to detect infection early in the incubation period.

The accessory cell populations in ulcerative colitis: a comparison between the colon and appendix in colitis and acute appendicitis.

We present an immunohistochemical study of accessory cells in acute appendicitis and ulcerative colitis (UC). By comparing these two diseases, it is possible to distinguish between changes associated with inflammatory bowel disease and those resulting from nonspecific intestinal inflammation. Nine total colectomy specimens from patients with UC, in which the appendix was also involved, were compared with nine cases of acute appendicitis. Accessory cells were stained for CD68 (PGMI), ACPI (acid cysteine proteinase inhibitor), S100 protein, MAC387 (calgranulin), CD1a, factor XIIIa, and WR18 (HLA class II). In ulcerative colitis, but not acute appendicitis, there was extension of a network of S100 positive dendritic cells into the crptal mucosa, and these S100-positive dendritic cells were closely aligned with the epithelium. The epithelium in UC, but not in acute appendicitis, showed intense upregulation of HLA class II, and this was particularly marked at the crypt bases. Dendritic, MAC387-positive cells were seen only in UC. In both diseases there were abundant ACPI-positive accessory cells in the cryptal areas, a population normally restricted to the dome areas. Factor XIIIa- and PGM1-positive cells, although abundant in both conditions, had distributions similar to those that we had previously shown in normal controls. No CD1a-positive cells were identified in either UC or acute appendicitis. We hypothesize that S100 identifies a subpopulation of activated macrophages. The concentration of this subpopulation, in close contact with the epithelium, which also shows altered expression of HLA class II antigens, suggests that a component of the immune response is targeting this area in UC. In addition, we also suggest that the identification of MAC387-positive dendritic cells in UC reflects increased macrophage turnover in inflammatory bowel disease.

CD5 is A potential selecting ligand for B-cell surface immunoglobulin: a possible role in maintenance and selective expansion of normal and malignant B cells.

Although the function of CD5 on B cells is unknown, previous studies suggested that CD5 interaction with V(H) framework regions of surface immunoglobulins (Igs) may contribute to survival and expansion of B cells. Here we used B-chronic lymphocytic leukemia (B-CLL) cells and transformed B-cell lines from normal and B-CLL patients to study CD5-Ig interactions. Immobilized Ig binds and permits isolation of CD5 from lysates of CD5-expressing cell lines. Immunoglobulins or Fab fragments of different V(H) families varied in their effectiveness as inhibitors of anti-CD5 staining of CLL cells, appendix and tonsil tissue sections. Human Ig also binds to purified recombinant CD5. We show here for the first time that the unconventional Ig-CD5 interaction maps to the extracellular CD5-D2 domain whereas conventional epitopes recognized by anti-CD5 antibodies are localized in the D1 domain of CD5. We propose that interactions of VH framework regions with CD5 as a ligand may maintain, select or expand normal, autoimmune or transformed B cells and also contribute to skewing of the normal V(H) repertoire.

Goblet cell carcinoid of the appendix.

A 47-year-old man was admitted with appendicitis, and appendectomy was performed. On microscopic examination of the resected specimen, the presence of goblet cell carcinoid in the tip of appendix was revealed. This tumor showed an aggressive nature with perineural and vascular invasion around the appendiceal serosa. The tumor was composed of two main cell populations: mucin-producing (goblet cell type) and silver-positive cells (endocrine differentiation). Additionally, a few cells were also positive for serotonin and lysozyme, but negative for gastrin and ACTH. These findings suggest that goblet cell carcinoid share some functional and histologic characteristics with carcinoid tumors and adenocarcinomas, although it is a distinct entity.

Prevalent abnormal prion protein in human appendixes after bovine spongiform encephalopathy epizootic: large scale survey.

OBJECTIVES: To carry out a further survey of archived appendix samples to understand better the differences between existing estimates of the prevalence of subclinical infection with prions after the bovine spongiform encephalopathy epizootic and to see whether a broader birth cohort was affected, and to understand better the implications for the management of blood and blood products and for the handling of surgical instruments. DESIGN: Irreversibly unlinked and anonymised large scale survey of archived appendix samples. SETTING: Archived appendix samples from the pathology departments of 41 UK hospitals participating in the earlier survey, and additional hospitals in regions with lower levels of participation in that survey. SAMPLE: 32,441 archived appendix samples fixed in formalin and embedded in paraffin and tested for the presence of abnormal prion protein (PrP). RESULTS: Of the 32,441 appendix samples 16 were positive for abnormal PrP, indicating an overall prevalence of 493 per million population (95% confidence interval 282 to 801 per million). The prevalence in those born in 1941-60 (733 per million, 269 to 1596 per million) did not differ significantly from those born between 1961 and 1985 (412 per million, 198 to 758 per million) and was similar in both sexes and across the three broad geographical areas sampled. Genetic testing of the positive specimens for the genotype at PRNP codon 129 revealed a high proportion that were valine homozygous compared with the frequency in the normal population, and in stark contrast with confirmed clinical cases of vCJD, all of which were methionine homozygous at PRNP codon 129. CONCLUSIONS: This study corroborates previous studies and suggests a high prevalence of infection with abnormal PrP, indicating vCJD carrier status in the population compared with the 177 vCJD cases to date. These findings have important implications for the management of blood and blood products and for the handling of surgical instruments.

Extranodal Rosai-Dorfman disease involving appendix and mesenteric nodes with a protracted course: report of a rare case lacking relationship to IgG4-related disease and review of the literature.

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare disease of unknown etiology that typically presents as nodal disease in young children. However, it also can present in various extranodal sites and can be difficult to recognize if not considered in the differential diagnosis. Here, we report a case of appendix involvement by extranodal RDD, which occurred in a 69-year-old woman with a long duration of 12 years for intermittent right lower quadrant pain. The patient underwent a right hemicolectomy for a clinical diagnosis of appendiceal cancer. A mixed inflammatory infiltration of mature lymphocytes, plasma cells and histiocytes exhibiting emperipolesis were indentified. Other areas had storiform fibrosis and sclerosis admixed with numerous plasma cells. These histologic features combination with immunoreactivity for CD68 and S100 protein were indicative of a diagnosis of extranodal RDD. We discuss the clinical, pathologic findings as well as differential diagnoses and consideration of a possible relationship of this entity to IgG4-related lesion.