Pattern-based Histologic Approach in Very Early Onset IBD: Main Features and Differential Diagnosis

Histologic alterations are common in Monogenic Disease patients with 'healthy' endoscopy: Results from a GIPAD-GIPPI multicenter study

OBJECTIVE

Very early-onset inflammatory bowel disease (VEO-IBD) is a clinical umbrella term referring to IBD-like symptoms arising in children before 6 years of age, encompassing 'pure' IBD (Crohn's Colitis/Ulcerative Colitis)/non IBD colitis, and monogenic diseases (MDs), the latter often related to primary immunodeficiency disorders. A multidisciplinary approach is imperative for correct therapeutic management, as endoscopy and histology are not always completely informative. In this setting, the study aims to describe the extent/features of histologic lesions in both endoscopically damaged mucosa and otherwise endoscopically healthy (normal/near normal) mucosa.

METHODS

Endoscopic data were retrospectively recorded, and histologic slides were collegially re-evaluated in a 93 VEO-IBD multicenter cohort, 76 (76/93 - 81,7 %) of which with complete endoscopic/histologic data.

RESULTS

At endoscopy, lesions were reported by the clinician in 66/76 (86,8 %) cases. When endoscopic lesions were reported, histologic damage was also seen. Interestingly, histologic mucosal damage was also documented in 43,3 % (13/30) of cases with endoscopically healthy/nearly healthy mucosa. This misalignment between endoscopy and pathology was seen in about a third of (29,1 % - 7/24) 'true' IBD and all MDs (100 % - 6/6) (p = 0.0029).

CONCLUSION

In VEO-IBD, histologic lesions can be present in endoscopically 'healthy' intestinal mucosa. This finding is more frequent in MDs, suggesting the need to accurately sample all the mucosal tract in VEO-IBD patients, even when no endoscopic lesions are seen at endoscopy.

Artificial intelligence: A new tool in the pathologist's armamentarium for the diagnosis of IBD

Inflammatory bowel diseases (IBD) are classified into two entities, namely Crohn's disease (CD) and ulcerative colitis (UC), which differ in disease trajectories, genetics, epidemiological, clinical, endoscopic, and histopathological aspects. As no single golden standard modality for diagnosing IBD exists, the differential diagnosis among UC, CD, and non-IBD involves a multidisciplinary approach, considering professional groups that include gastroenterologists, endoscopists, radiologists, and pathologists. In this context, histological examination of endoscopic or surgical specimens plays a fundamental role. Nevertheless, in differentiating IBD from non-IBD colitis, the histopathological evaluation of the morphological lesions is limited by sampling and subjective human judgment, leading to potential diagnostic discrepancies. To overcome these limitations, artificial intelligence (AI) techniques are emerging to enable automated analysis of medical images with advantages in accuracy, precision, and speed of investigation, increasing interest in the histological analysis of gastrointestinal inflammation. This review aims to provide an overview of the most recent knowledge and advances in AI methods, summarizing its applications in the histopathological analysis of endoscopic biopsies from IBD patients, and discussing its strengths and limitations in daily clinical practice.

Clinicopathologic Features of Primary Immunodeficiency Monogenic Disease-related Very Early Onset Inflammatory Bowel Disease: Focus on Gastrointestinal Histologic Features in IFIH1 Mutations

Very early onset inflammatory bowel disease (VEO-IBD) is a clinical term referring to IBD-like symptomatology arising in children younger than 6 years. VEO-IBD may be due to polygenic etiology in "pure" IBD (Crohn disease-CD and ulcerative colitis-UC), or it may be caused by primary immunodeficiency underlined by monogenic disease. Primary immunodeficiency monogenic diseases have a Mendelian inheritance and affect the immune system with multiorgan morbidity and possible effects on the gastrointestinal system. Primary Immunodeficiency monogenic diseases differ from "pure" IBD as the latter primarily affect the gastrointestinal tract with mitigated extraintestinal symptomatology. Since their first description, primary immunodeficiency monogenic diseases, although rare, have been the subject of increasing interest due to their dramatic phenotype, difficulty in reaching a timely diagnosis, and specific therapeutic approach. In this paper, we present a brief review of primary immunodeficiency monogenic diseases, focusing on to their clinicopathologic features as well as delving, in greater detail, into monogenic diseases caused by IFIH1 mutations. The clinicopathologic features of 4 patients with IFIH1, a gene involved in interferon pathway deficiency, will be described using a histologic pattern of damage approach confirming the need to avoid the histologic diagnosis of VEO-IBD in children younger than 6 years.

Genomic testing identifies monogenic causes in patients with very early-onset inflammatory bowel disease: a multicenter survey in an Iranian cohort

Patients with very early-onset inflammatory bowel disease (VEO-IBD) may present because of underlying monogenic inborn errors of immunity (IEI). Strong differences have been observed in the causes of monogenic IBD among ethnic populations. This multicenter study was carried out on 16 Iranian patients with VEO-IBD. We reviewed clinical and basic immunologic evaluation including flow cytometry and immunoglobulin levels. All patients underwent clinical whole exome sequencing (WES). Sixteen patients (8 females and 8 males) with a median age of 43.5 months were enrolled. The median age at the onset of symptoms was 4 months. Most patients (12, 75%) had consanguineous parents. Chronic non-bloody diarrhea (13, 81.3%) and perianal diseases including perianal abscess (6, 37.5%), anal fissure (6, 37.5%), or anal fistula (2, 12.5%) were the most common manifestations. WES identified a spectrum of genetic variants in 13 patients (81.3%): IL10RB (6, 37.5%), MVK (3, 18.8%), and CASP8, SLC35C1, G6PC3, and IKBKB in 1 patient, respectively. In 3 patients (18.7%), no variant was identified. Flow cytometry identified a spectrum of abnormalities that helped to assess the evidence of genetic diagnosis. At the end of the survey, 3 (18.8%) patients were deceased. This high rate of monogenic defects with a broad spectrum of genes reiterates the importance of investigating IEI in patients with infantile-onset IBD.

Application of a pattern-based approach to histological diagnosis in very early onset IBD (VEO-IBD) in a multicentric cohort of children with emphasis on monogenic disease with IBD-like morphology

AIMS

Very early-onset inflammatory bowel disease (VEO-IBD) is a clinical umbrella term referring to IBD-like symptoms arising in children before the age of 6 years, encompassing both 'pure' IBD, such as ulcerative colitis (UC) and Crohn's disease (CD) and monogenic diseases (MDs), the latter often involving genes associated with primary immunodeficiencies. Moreover, histological features in gastrointestinal (GI) biopsies in MD can also have IBD-like morphology, making differential diagnosis difficult. Correct diagnosis is fundamental, as MDs show a more severe clinical course and their inadequate/untimely recognition leads to inappropriate therapy.

METHODS AND RESULTS

Biopsy samples from the lower and upper GI tract of 93 clinically diagnosed VEO-IBD children were retrospectively selected in a multicentre cohort and histologically re-evaluated by 10 pathologists blinded to clinical information. Each case was classified according to morphological patterns, including UC-like; CD-like; enterocolitis-like; apoptotic; eosinophil-rich; and IBD-unclassified (IBD-U). Nine (69%) MD children showed IBD-like morphology; only the IBD-U pattern correlated with MD diagnosis (P = 0.02) (available in 64 cases: 51 non-MD, true early-onset IBD/other; 13 MD cases). MD patients showed earlier GI symptom onset (18.7 versus 26.9 months) and were sent to endoscopy earlier (22 versus 37 months), these differences were statistically significant (P < 0.05). Upper GI histology was informative in 37 biopsies.

CONCLUSIONS

The diagnosis of the underlying cause of VEO-IBD requires a multidisciplinary setting, and pathology, while being one of the fundamental puzzle pieces, is often difficult to interpret. A pattern-based histological approach is therefore suggested, thus aiding the pathologist in VEO-IBD reporting and multidisciplinary discussion.

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.