"Stranger things" in the gut: uncommon items in gastrointestinal specimens

The effect of Entamoeba histolytica lectin antigen and microRNA-643 on the development of microsatellite instability (MSI) in colorectal adenocarcinoma

Entamoeba histolytica remains a significant cause of global mortality. The involvement of protozoa in microsatellite instability (MSI) and the potential of miRNA-643 as biomarkers for amoebic and colorectal diseases have not been extensively researched. The relationship between the antigenic structure of Entamoeba histolytica Lectin (Eh-lectin) and the altered expression of miRNA-643 and the X-Linked Inhibitor of Apoptosis (XIAP) is still unclear. This study aimed to identify Eh-lectin, miRNA-643, XIAP, and MSI in 150 colorectal cancer biopsy samples using a comprehensive approach that included immunohistochemistry (IHC), Multiplex PCR, RT-qPCR, and Real-Time PCR. To enhance the accuracy of MSI diagnosis, PCR-Multiplex was performed alongside IHC. Among the 150 colorectal cancer biopsy samples analyzed, 39 (comprising 28 MSI-H and 11 MSI-L) showed MSI, while the remaining 111 were MSI-negative. Notably, 11 samples demonstrated a co-occurrence of MSI and Eh-lectin, with increased expression of miRNA-643 relative to XIAP. The presence of MSI in conjunction with Eh-lectin positivity and elevated miRNA-643 expression, along with reduced levels of the XIAP inhibitor gene in colorectal adenocarcinoma biopsy samples, strongly indicates that this protozoan parasite may play a role in the development of MSI by affecting apoptosis.

Pericardial anisakiasis: unravelling diagnostic challenges in an unprecedented extra-abdominal manifestation: a case report

Background

Anisakis infects humans by consuming contaminated undercooked or raw fish, leading to gastric anisakiasis, gastro-allergic anisakiasis, or asymptomatic contamination. Although larvae usually die when penetrating the gastric tissue, cases of intra- and extra-abdominal spread were described. We report the first probable case of pericardial anisakiasis.

Case summary

A 26-year-old man presented to the emergency department because of progressive lower limb oedema and exertional dyspnoea. Two months prior, he had consumed raw fish without any gastrointestinal symptoms. The echocardiogram reported a circumferential pericardial effusion ('swinging heart') and mildly reduced left ventricular ejection fraction (LVEF). He was diagnosed with myopericarditis after a cardiac magnetic resonance. A fluorodeoxyglucose positron emission tomography scan revealed an intense pericardial metabolism. Blood tests exhibited persistent eosinophilia and mild elevation of Anisakis simplex IgE-as for past infestation. A pericardial drainage was performed, subsequently, serial echocardiograms revealed a spontaneous recovery of his LVEF. No autoimmune, allergic, or onco-haematologic diseases were identified. Based on a history of feeding with potentially contaminated raw fish and on long-lasting eosinophilia, we suspected a pericardial anisakiasis, despite a low but persistent titre of specific IgE. Albendazole was administered for 21 days, along with colchicine and ibuprofen for 2 months; pericardial effusion resolution and eosinophil normalization occurred two weeks after.

Discussion

We hypothesized that Anisakis larvae may have migrated outside the gastrointestinal tract, penetrating the diaphragm and settling in the pericardium, causing pericarditis and pericardial effusion. Clinicians should know that the pericardium may be another extra-abdominal localization of anisakiasis, beyond pleuro-pulmonary involvement.

Pathologie infectieuse du tube digestif : diagnostics à ne pas manquer

Le contexte récent du COVID-19 a renouvelé l’intérêt des pathologistes pour les maladies d’origine infectieuse. Cet intérêt est d’autant plus fort dans le tube digestif où les symptômes sont aspécifiques, souvent frustres avec un aspect endoscopique normal entraînant parfois une errance diagnostique. Dans ce contexte, les biopsies systématiques réalisées par le clinicien sont parfois le seul moyen de parvenir au diagnostic. Néanmoins, le diagnostic précis de ses pathologies nécessite une bonne connaissance à la fois du contexte de survenue de ces pathologies, de l’aspect histopathologique et d’une analyse rigoureuse utilisant des colorations spéciales et/ou des analyses immunohistochimiques. Certaines pathologies infectieuses du tube digestif sont bien connues par les pathologistes qui sont largement sollicités dans leurs diagnostics (gastrite à Helicobacter pylori, œsophagite à Candida albicans ou la colite à CMV), mais d’autres sont plus délicates à diagnostiquer. Dans cet article, nous présenterons, après avoir rappelé les différentes colorations spéciales utiles, des pathologies bactériennes ou parasitaires rares ou de diagnostic difficile « à ne pas manquer » dans le tube digestif.

Intestinal pseudo-obstruction caused by Giardia lamblia infection

A woman in her 40s presented with malaise, nausea, reduced appetite, abdominal distention, loose stools and weight loss. Symptoms had started 6 months earlier and worsened in the last 2 weeks. CT enterography showed hypotonic dilated small bowel loops in absence of any mechanical obstruction. Endoscopic examinations including capsule endoscopy did not reveal any obstructing lesion, but a delayed small bowel transit time of the capsule. Duodenal histology revealed Marsh 3a villous atrophy. Secondary causes of intestinal pseudo-obstruction and villous atrophy were investigated. Giardia lamblia trophozoites were found in the stools and in the duodenal biopsies. The patient's symptoms quickly resolved after metronidazole treatment with complete normalisation of duodenal histology.

Entamoeba histolytica and Probable Effect on Production Microsatellite Instability in Colorectal Cancer

The mortality rate of Entamoeba histolytica is still high and approximately 100,000 per year. Environmental factors and different pathogens can cause microsatellite instability (MSI) positive, which may be one reason for colorectal cancer. MSI status can play an essential role in treatment. Moreover, E. histolytica might be one of the pathogens which raise the incidence of colorectal cancer. Therefore, the probable relationship of E. histolytica with MSI production was evaluated. Four hundred samples of colorectal biopsies based on pathological reports were divided into four groups: colitis, polyps, hyperplasia or dysplasia, and adenocarcinoma. The prevalence of E. histolytica was examined with PCR and immunohistochemical staining (IHC) for the light chain lectin HK-9. The adenocarcinoma formalin-fixed paraffin-embedded colorectal tumours sections were tested for MSI genes. We detected E. histolytica in 6% and 4% of colitis samples by PCR and IHC technique, respectively. However, it did not identify in polyp and hyperplasia samples. The MSI test was examined in the colorectal cancer group, which became positive in 19%. Entamoeba histolytica was detected in 26.3% (5/19) of MSI-positive and 2.5% (2/81) of MSI-negative cases by IHC technique however was not identified by PCR assay in this group. It is concluded PCR and IHC assay is recommended as complementary tests in colitis biopsies. Simultaneous PCR and IHC negative results could confirm the non-existence of the parasite with more confidence. Consequently, E. histolytica might be one of the biotic  factors which raise the incidence of colorectal cancer because of the coincidence of the IHC positive results in MSI-positive adenocarcinoma.

Pathologist's approach to paediatric and neonatal eosinophilic gastrointestinal disorders

Children are not simply miniature adults. The evaluation of their gastrointestinal disorders is therefore different from that in full-grown adults and requires a particular clinical/pathologic approach. Different studies have tried to assess the normal eosinophil distribution in the gastrointestinal tract in adults while very few studies have investigated the paediatric population, consequently complicating the pathologist's ability in identifying an abnormal number of eosinophils in this setting of patients. When evaluating gastrointestinal tract biopsies with eosinophilia, eosinophilic count must be considered along with other histological features like eosinophil distribution in the gastrointestinal wall, their degranulation, cryptitis and crypt abscesses, other accompanying inflammatory cells, apoptotic bodies, foreign material or microorganisms; these findings, although rarely specific, may be a useful aid for diagnosis. Reports should not include a diagnosis of primary eosinophilic gastrointestinal disorders (EoGID) if clinical data and test results do not rule out other forms of gastrointestinal eosinophilia. A more descriptive definition like "with eosinophilic pattern" should be favoured over a specific diagnosis of "eosinophilic disorder" in order to avoid potential confusion between different entities.