Significance of intraepithelial lymphocytes in appendix

The appendix and ulcerative colitis - an unsolved connection

The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant.

The vermiform appendix: an immunological organ sustaining a microbiome inoculum

The hominoid vermiform appendix has been characterized as a diverticulum of the caecum and describes an entity at the juxtaposition of the colon in the confluence of tanias. The independent development of the lymphoid follicle centres of the appendix is progressed at birth in the presence of the intestinal commensal microbiome, an obligatory prompt for the diversification of intestinal and extra-intestinal mucosal immunological tissue. In the vermiform appendix, this activity is centred on further developing the inventory of primary antibodies and the maturation of T- and B-lymphocyte cells in the follicles within the lymphoid tissue. Furthermore, the columnar epithelia, enterocytes and goblet cells comprise the complement of cells that occupy the lamina propria and muscularis mucosae of the vermiform appendix's mucosa, while macrophages and an abundance of immunoglobulin A and immunoglobulin G generating plasma cells seed the lamina propria Intraepithelial immune cells consisting predominantly of specific CD8⁺ T regulatory lymphocytes occupy sites in the appendix analogous to those present in the intestinal epithelia of the caecal colon. The complement of bacterial genera concealed in the vermiform appendix is posited extant as a biofilm inoculum of the intestinal commensal microbiome. This facilitates re-inoculation of the proximal colon and to a lesser degree the terminal ilium post an intestinal perturbation such as occurs with daily lifestyle stressors, dietary choices and the short-term administration of antibiotics rather than an infectious fulminant colitis. A plausible appreciation results of the importance of multiple immunological aspects of a healthy vermiform appendix and the provision of a commensal biofilm to the gut that repairs a dysbiotic microbiome contributing to balancing intestinal pro- and anti-inflammatory activity for maintaining homeostasis in the gut. Since the composition of the gut microbiome can vary over the short-term and long-term, it is plausible that the appendix inoculum may be instrumental in maintaining the intestinal microbiome.

The immunology of the vermiform appendix: a review of the literature

This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of the appendiceal biofilm in particular has proved to have a beneficial effect for the entire gut. In assessing the influence of acute appendicitis and the importance of a normally functioning gut flora, however, multiple immunological aspects point towards the appendix as a priming site for ulcerative colitis. Describing the immunological and microbiotical changes in the appendix during acute and chronic inflammation of the appendix, this review suggests that this association becomes increasingly plausible. Sustained by the distinct composition of cells, molecules and microbiota, as well as by the ever more likely negative correlation between the appendix and ulcerative colitis, the idea of the appendix being a vestigial organ should therefore be discarded.

Is Enterobius vermicularis infestation associated with acute appendicitis?

PURPOSE

Enterobius vermicularis might be seen in specimens of patients who underwent surgery due to acute appendicitis. There is still debate as to E. vermicularis infestation causes acute appendicitis. The primary aim of this study is to determine the incidence of E. vermicularis infestation, and the secondary aim is to determine the possible role of E. vermicularis in pathogenesis of appendicitis as well as the adequacy of demographic data and laboratory values in predicting infestation preoperatively.

METHODS

A retrospective investigation was conducted with all patients who underwent appendectomy due to acute appendicitis in a secondary care center. Patients with E. vermicularis were compared with 24 controls that underwent appendectomy during the same time period. Demographic data, preoperative white blood cell (WBC) count, eosinophil counts, and histopathological findings for both groups were analyzed and compared.

RESULTS

Enterobius vermicularis was detected in the appendectomy materials in 9 of 1446 patients (0.62 %). Histopathologically, only one of nine patients had acute appendicitis while the others were diagnosed with lymphoid hyperplasia. There were no statistically significant differences between the groups except WBC count. However, the WBC count was significantly (p < 0.05) lower in the group which was detected E. vermicularis.

CONCLUSIONS

Enterobius vermicularis is rarely associated with the histopathological findings of acute appendicitis. Also eosinophil count and elevation of white blood counts are inadequate for predicting preoperative E. vermicularis.

Unusual histopathological findings in appendectomy specimens: A retrospective analysis and literature review

AIM: To document unusual findings in appendectomy specimens.

METHODS: The clinicopathological data of 5262 patients who underwent appendectomies for presumed acute appendicitis from January 2006 to October 2010 were reviewed retrospectively. Appendectomies performed as incidental procedures during some other operation were excluded. We focused on 54 patients who had unusual findings in their appendectomy specimens. We conducted a literature review via the PubMed and Google Scholar databases of English language studies published between 2000 and 2010 on unusual findings in appendectomy specimens.

RESULTS: Unusual findings were determined in 54 (1%) cases by histopathology. Thirty were male and 24 were female with ages ranging from 15 to 84 years (median, 32.2 ± 15.1 years). Final pathology revealed 37 cases of enterobiasis, five cases of carcinoids, four mucinous cystadenomas, two eosinophilic infiltrations, two mucoceles, two tuberculosis, one goblet-cell carcinoid, and one neurogenic hyperplasia. While 52 patients underwent a standard appendectomy, two patients who were diagnosed with tuberculous appendicitis underwent a right hemicolectomy. All tumors were located at the distal part of the appendix with a mean diameter of 6.8 mm (range, 4-10 mm). All patients with tumors were alive and disease-free during a mean follow-up of 17.8 mo. A review of 1366 cases reported in the English literature is also discussed.

CONCLUSION: Although unusual pathological findings are seldom seen during an appendectomy, all appendectomy specimens should be sent for routine histopathological examination.

Presenting features of Enterobius vermicularis in the vermiform appendix

OBJECTIVE

Enterobius vermicularis (pinworm) infestation can present with symptoms resembling acute appendicitis, although current evidence suggests that it does not necessarily cause acute appendicitis. The purpose of this study was to characterize the clinical presentation of patients with pinworms in the vermiform appendix and to establish features suggestive of this condition.

MATERIAL AND METHODS

A retrospective analysis of all patients undergoing appendicectomy with appendicular pinworms between 1998 and 2003 was undertaken. Patients were compared against 54 controls with confirmed acute suppurative appendicitis from the same time period. Presenting features, vital signs and modified Alvarado scores were obtained from the patients' records.

RESULTS

Eighteen out of 1150 patients (1.5%) undergoing appendicectomy were proven to have pinworms (age range 8-37 years, 12 F, 6 M). Two of 18 appendices containing pinworms showed evidence of inflammation. Patients with pinworms had significantly lower white cell counts (WCCs) than the control group (median 8.9 versus 14.7, p=0.045), lower total Alvarado scores (median 5.5 versus 7, p=0.01) and were more likely to have had recurrent episodes of right iliac fossa (RIF) pain and previous hospital admissions (p<0.001).

CONCLUSIONS

E. vermicularis infestation of the appendix should be considered in the differential diagnosis of patients who present with recurrent RIF pain but do not have a significantly raised WCCs, or high Alvarado scores. These patients should be investigated with early fecal sampling and night-time application of cellophane tape, and they may benefit from empirical antiparasitic treatment.