Practical pathology and genetics of Hirschsprung's disease

Evaluation and Management of Total Colonic Hirschsprung Disease: A Comprehensive Review From the American Pediatric Surgical Association (APSA) Hirschsprung Disease Interest Group

BACKGROUND

Children with total colonic Hirschsprung disease (TCHD) are a unique group of patients with pre- and postoperative management challenges. This review provides a rational, expert-based approach to diagnosing and managing TCHD.

METHODS

The guidelines were developed by the Hirschsprung Disease Interest Group members established by the American Pediatric Surgical Association (APSA) Board of Governors. Group discussions, literature review, and expert consensus were used to summarize the current knowledge regarding diagnosis, staged approach, the timing of pull-through, and pre-and postoperative management in children with TCHD.

RESULTS

This paper presents recommendations for managing TCHD before and after reconstruction, including diagnostic criteria, surgical approaches, bowel management, diet, antibiotic prophylaxis, colonic irrigations, and post-surgical considerations.

CONCLUSIONS

A clear understanding of the unique challenges posed by TCHD and consensus on its treatment are lacking in the literature. This review standardizes this patient group's pre- and postoperative management.

LEVEL OF EVIDENCE

V.

The Diagnostic Pathway of Hirschsprung's Disease in Paediatric Patients: A Single-Centre Experience

BACKGROUND

The presenting symptoms of patients with Hirschsprung's disease (HD) are a failure to pass meconium, abdominal distension, and bilious vomiting. The gold standard diagnosis is a rectal biopsy to confirm aganglionosis. The aim of our study was to describe the diagnostic pathway of Hirschsprung's disease at our institution and document the indication for a rectal biopsy.

METHODS

We have performed a prospective collection of all patients who underwent a rectal biopsy to exclude HD from December 2022 until September 2023 including. The following data were collected: patient's age, presenting symptoms, type of biopsy, failure rate, complications, and histopathological results.

RESULTS

We identified 33 patients who underwent 34 rectal biopsies at 0.6 years of age. A total of 17 patients had a rectal suction biopsy (RSB), and 17 patients underwent a partial thickness under general anaesthesia (GA). 1/17 (6%) patients had an inconclusive RSB and subsequently underwent a biopsy under GA. Constipation and chronic abdominal distension plus vomiting were the most common presenting symptoms throughout all ages. Five patients (15%) had a rectal biopsy that was positive for HD.

CONCLUSION

A protocolised approach to the assessment of infants and children with suspected HD ensures the appropriate utilisation of invasive procedures such as biopsy.

Enough is enough: how many rectal suction biopsies do you need to diagnose Hirschsprung's disease?

PURPOSE

Rectal suction biopsy (RSB) is the gold standard for diagnosing Hirschsprung's disease (HD) in infants. Despite being a common procedure, no standard exists on the number of biopsy specimens and their respective level within the rectum.

METHODS

We conducted a retrospective review of epidemiological and pathological data of patients who underwent RSB at our institution between January 2011 and May 2022. During RSB we obtain 4 specimens: at 1 cm, 3 cm and 5 cm above the dentate line, besides one specimen at the dentate line. We used a logistic regression model for statistical analysis and included control variables (e.g. underlying disease, weight at first biopsy, gestational age).

RESULTS

A total of 92 patients underwent 115 biopsies, with an average of 3.77 specimens per session. Of the specimens taken at 1 cm above the dentate line 73.9% were conclusive, at 3 cm 75.9% and at 5 cm 79.2%. Specimens taken at the dentate line were squamous or transitional epithelia in 31.5% and therefore of no use for HD diagnostics. The specimen at 3 cm shows the highest discriminative power whether the biopsy session was diagnostic (p-value < 1%).

CONCLUSIONS

We propose that a total of three specimens, namely one at 1 cm, one at 3 cm and one at 5 cm above the dentate line, is enough to diagnose or exclude HD.

Enteric Nervous System Striped Patterning and Disease: Unexplored Pathophysiology

The enteric nervous system (ENS) controls gastrointestinal (GI) motility, and defects in ENS development underlie pediatric GI motility disorders. In disorders such as Hirschsprung's disease (HSCR), pediatric intestinal pseudo-obstruction (PIPO), and intestinal neuronal dysplasia type B (INDB), ENS structure is altered with noted decreased neuronal density in HSCR and reports of increased neuronal density in PIPO and INDB. The developmental origin of these structural deficits is not fully understood. Here, we review the current understanding of ENS development and pediatric GI motility disorders incorporating new data on ENS structure. In particular, emerging evidence demonstrates that enteric neurons are patterned into circumferential stripes along the longitudinal axis of the intestine during mouse and human development. This novel understanding of ENS structure proposes new questions about the pathophysiology of pediatric GI motility disorders. If the ENS is organized into stripes, could the observed changes in enteric neuron density in HSCR, PIPO, and INDB represent differences in the distribution of enteric neuronal stripes? We review mechanisms of striped patterning from other biological systems and propose how defects in striped ENS patterning could explain structural deficits observed in pediatric GI motility disorders.

A new systematization of histological analysis for the diagnosis of Hirschsprung's disease

BACKGROUND

Hirschsprung's Disease (HD) is characterized by intestinal sub-occlusion and the absence of enteric ganglion cells. A rectal biopsy examination is performed to confirm the diagnosis. In a recent study, we demonstrated that the analysis of 60 sections of rectal mucosa and submucosa stained by H&E may ensure a 90% diagnostic accuracy. Although the need to analyze so many sections makes the process of reading the slides more time-consuming, this encouraged us to study their distribution in the healthy rectal submucosa, to simplify the diagnosis.

OBJECTIVES

To develop a method that facilitates HD diagnosis by studying the distribution of ganglion cells in the submucosal plexus.

METHODS

Using the calretinin technique, we studied the distribution of plexuses in 60 fragments of rectal submucosa from 19 cadavers. After the study, the reading method created was used for diagnosis in 47 cases of suspected HD, using H&E staining. The accuracy was verified by comparing the results obtained with H&E to those obtained with the acetylcholinesterase technique, the golden standard in our laboratory.

RESULTS

The study of submucosal plexus distribution showed that just by examining the submucosal region every 20 µm, approximately, it is possible to locate a ganglionic plexus, and we have already been able to diagnose HD with 93% accuracy.

CONCLUSION

The study of ganglion cell distribution enabled the creation of a simplified method for reading the slides. The method applied achieved good accuracy and it can be used as an alternative method in HD diagnosis.

Neuroimmune regulation in Hirschsprung's disease associated enterocolitis

Neuroimmune pathways are important part of the regulation of inflammatory response. Nerve cells regulate the functions of various immune cells through neurotransmitters, and then participate in the inflammatory immune response. Hirschsprung's disease (HD) is a congenital abnormal development of intestinal neurons, and Hirschsprung-associated enterocolitis (HAEC) is a common complication, which seriously affects the quality of life and even endangers the lives of children. Neuroimmune regulation mediates the occurrence and development of enteritis, which is an important mechanism. However, there is a lack of review on the role of Neuroimmune regulation in enterocolitis associated with Hirschsprung's disease. Therefore, this paper summarizes the characteristics of the interaction between intestinal nerve cells and immune cells, reviews the neuroimmune regulation mechanism of Hirschsprung's disease associated enterocolitis (HAEC), and looks forward to the potential clinical application value.

Children with Hirschsprung disease in a developing country: A cohort study of the predictors of a positive rectal biopsy result

Chronic constipation, which may be habitually or pathologically caused, is one of the most common complaints in children. One of the important pathological causes is Hirschsprung's disease (HD), which is diagnosed via multiple modalities, mainly rectal biopsy. Our aim was to compare the presentation and different predictive factors for positive rectal biopsy results in a developing country in the Middle East, such as Jordan. This cohort study was conducted at the Jordan University Hospital (JUH). All consecutive children aged <14 years who presented with refractory constipation and underwent rectal biopsies between January 2014 and December 2019 were retrospectively enrolled in the study. In the entire cohort study, 79 patients were enrolled: 45 (57%) were males and 34 (43%) were females. Regarding the biopsy results, 51 (64.6%) cases of refractory constipation without HD and 28 (35.4%) patients with refractory constipation with HD were diagnosed with open rectal biopsies. The male-to-female ratio of HD patients was 3:1. Moreover, 3 (10.7%) children who passed the meconium within the first 24 to 48 hours showed features of HD, while 17 (60.7%) children with delayed passage of the meconium showed features of HD. Abdominal distension was found to be a positive predictor of positive biopsy results (odds ratio [OR] = 4.09, P = .011), and soiling was found to be a negative predictor of positive biopsy results (OR = 0.07, P = .024). In developing countries, children presenting with HD seem to have similar symptoms and signs to those observed with traditional sampling and staining techniques.

A Novel Method for Identifying the Transition Zone in Long-Segment Hirschsprung Disease: Investigating the Muscle Unit to Ganglion Ratio

Hirschsprung disease (HSCR) is characterised by the absence of enteric ganglia along variable lengths of the distal bowel. Current gold standard treatment involves the surgical resection of the defective, aganglionic bowel. Clear and reliable distinction of the normoganglionated bowel from the transition zone is key for successful resection of the entire defective bowel, and the avoidance of subsequent postoperative complications. However, the intraoperative nature of the tissue analysis and the variability of patient samples, sample preparation, and operator objectivity, make reproducible identification of the transition zone difficult. Here, we have described a novel method for using muscle units as a distinctive landmark for quantifying the density of enteric ganglia in resection specimens from HSCR patients. We show that the muscle unit to ganglion ratio is greater in the transition zone when compared with the proximal, normoganglionated region for long-segment HSCR patients. Patients with short-segment HSCR were also investigated, however, the muscle unit to ganglion ratio was not significantly different in these patients. Immunohistochemical examination of individual ganglia showed that there were no differences in the proportions of either enteric neurons or glial cells through the different regions of the resected colon. In addition, we identified that the size of enteric ganglia was smaller for patients that went on to develop HSCR associated enterocolitis; although the density of ganglia, as determined by the muscle unit to ganglia ratio, was not different when compared with patients that had no further complications. This suggests that subtle changes in the enteric nervous system, even in the “normoganglionated” colon, could be involved in changes in immune function and subsequent bacterial dysbiosis.

Association between IKBKAP polymorphisms and Hirschsprung's disease susceptibility in Chinese children

BACKGROUND

Hirschsprung's disease (HSCR) is a rare congenital disease in which enteric nervous system (ENS) in the distal intestine is absent. HSCR is a disease involving genetic factors and environmental factors. Despite a series of genes have been revealed to contribute to HSCR, many HSCR associated genes were yet not identified. Previous studies had identified that a potential susceptibility gene of HSCR was an inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase complex-associated protein (IKBKAP). The study aimed to explore the association of genetic variants in IKBKAP and HSCR susceptibility in southern Chinese children.

METHODS

Single nucleotide polymorphism (SNPs) were genotyped by the Mass ARRAY iPLEX Gold system (Sequenom, San Diego, CA, USA) on all samples, which included 1,470 HSCR children (cases) and 1,473 healthy children (controls). The associations between SNPs and HSCR or clinical subtypes were assessed by comparing their allele frequencies in corresponding case and control samples. Different genetic models, including additive, recessive, and dominant models, were tested using PLINK 1.9 software.

RESULTS

Further subgroup analysis revealed rs2275630 as a total colonic aganglionosis (TCA)-specific susceptibility locus. The present study is the first to indicate that IKBKAP rs2275630 were associated with HSCR susceptibility, especially in TCA patients.

CONCLUSIONS

We conclude that IKBKAP rs2275630 is a susceptibility gene of HSCR.

Focal adhesion-mediated cell anchoring and migration: from in vitro to in vivo

Cell-extracellular matrix interactions have been studied extensively using cells cultured in vitro. These studies indicate that focal adhesion (FA)-based cell-extracellular matrix interactions are essential for cell anchoring and cell migration. Whether FAs play a similarly important role in vivo is less clear. Here, we summarize the formation and function of FAs in cultured cells and review how FAs transmit and sense force in vitro. Using examples from animal studies, we also describe the role of FAs in cell anchoring during morphogenetic movements and cell migration in vivo. Finally, we conclude by discussing similarities and differences in how FAs function in vitro and in vivo.

Diagnostic accuracy of calretinin and acetylcholinesterase staining of rectal suction biopsies in Hirschsprung disease examined by unexperienced pathologists

Rectal suction biopsy (RSB) is a gold standard for diagnosing Hirschsprung disease (HD). Calretinin staining of RSB is increasingly used by experienced pathologists due to non-complex examination and comparable diagnostic accuracy with acetylcholinesterase (AChE). However, the diagnostic accuracy of calretinin examined by unexperienced pathologists remains to be elucidated. Therefore, we aim to compare diagnostic accuracy of calretinin with AChE on RSB for diagnosing HD when examined by unexperienced pathologists. We prospectively analyzed sections from RSB stained with AChE + HE and calretinin. Blinded examination was done by five unexperienced pathologists (pathology residents) and three experienced pathologists (senior pediatric gastro-enterology pathologists) assessing for the presence of HD. Cases for the study included ones proven to be HD on resection specimens and cases without HD. Diagnostic accuracy was determined calculating area under the curve (AUC), sensitivity, specificity, likelihood ratio, and posttest probability. Fleiss’ kappa analysis was performed to assess interobserver agreement between reviewers. Eleven of 18 included patients (61%) were diagnosed with HD. Comparing the diagnostic accuracy of unexperienced pathologists, calretinin versus AChE + HE showed sensitivity of 80.0% versus 74.5% and specificity of 100% versus 65.4%, AUC of 0.87 (0.78–0.96) versus 0.59 (0.45–0.72). Unexperienced pathologists showed substantial agreement with calretinin (kappa 0.72 [0.61–0.84]) and fair agreement with AChE + HE (kappa 0.34 [0.23–0.44]). We found calretinin having higher diagnostic accuracy in diagnosing HD compared to AChE + HE when examined by unexperienced pathologists. Therefore, we recommend to use calretinin as the standard technique for staining RSB in diagnosing HD.

Increasing Trend of Calretinin-Positive Mucosal Innervation from Aganglionic Zone toward Transition Zone in Hirschsprung's Disease

INTRODUCTION

 Diagnosis of very short-segment Hirschsprung's disease (vsHD) by rectal suction biopsy is challenging as its aganglionic zone (AZ) overlaps with physiologic hypoganglionic zone and calretinin-positive mucosal nerves may extend from the transition zone (TZ) into AZ. We studied whether an increasing trend/gradient of calretinin-positive mucosal nerves along the distance from AZ toward TZ aids in diagnosis of HD.

MATERIALS AND METHODS

 In this study, 46 rectal suction biopsies from non-HD and HD, and 15 pull-through specimens from short-segment HD were evaluated by mucosal calretinin immunostain (CI) and image processing and analysis (IPA) to measure pixel count (PC, the percentage of calretinin stained pixels in the mucosa). Consecutive longitudinal sections of proximal AZ toward distal TZ in HD pull-through specimens were utilized as a vsHD surrogate model. First, we studied variability of mucosal CI in non-HD biopsies along the distance from dentate line. Second, we determined a cutoff point of mucosal CI by IPA that separated non-HD versus HD and applied this cutoff to longitudinal sections from proximal AZ to distal TZ segments in HD pull-through specimens. Third, we studied whether an increasing trend of mucosal CI was universally observed in HD pull-through.

RESULTS

 Our findings included a significant variability in PC along the biopsy distance in non-HD cases. Positive mucosal CI was found in proximal AZ in 6 (43%) of 14 HD pull-through, among which 1 case lacked submucosal nerve hypertrophy in the proximal AZ. All 14 HD pull-through cases showed an increasing trend/gradient of PC from AZ toward TZ.

CONCLUSION

 Based on our findings, the presence or absence of mucosal CI positivity and submucosal nerve hypertrophy may not reliably diagnose vsHD in rectal suction biopsy. While we acknowledge that the density of mucosal innervation in variable contexts and anatomical locations is unknown and yet to be explored, our study suggests that an increasing trend of positive mucosal CI from AZ toward TZ by IPA might prove to be a useful tool for the diagnosis of vsHD in the future.

Diagnostic Efficacy of Rectal Suction Biopsy with Regard to Weight in Children Investigated for Hirschsprung's Disease

BACKGROUND/AIM

Diagnostic efficacy, defined as the percentage of rectal suction biopsy (RSB) specimens sufficient enough to determine the absence of ganglia cells in Hirschsprung's disease (HD) diagnosis, has been reported to be low, requiring repeated biopsies. The aim was to explore whether RSB diagnostic efficacy was influenced by the child's weight and to ascertain whether RSB efficacy differed between aganglionic and ganglionic tissue.

MATERIALS AND METHODS

Efficacy analyses were conducted in a national HD-center's register on children 0-15 kg, examined between 2011-2019. First-time RSB diagnostic efficacy was correlated to the children's weight and final HD diagnosis.

RESULTS

Among the 84 children who had first-time RSB, the overall diagnostic efficacy was 85% (71/84). The efficacy was higher among children weighing less than the identified cut-off of 9.0 kg (89% in 0-9.0 kg versus 62% in 9.01-15.0 kg, p = 0.026). Among children diagnosed with HD, 96% (26/27) weighed 0-9.0 kg. In this weight group, the diagnostic efficacy was lower in aganglionosis compared to ganglionosis (77%; 20/26 versus 96%; 43/45), p = 0.045).

CONCLUSIONS

The RSB diagnostic efficacy was significantly higher in children weighing less than 9.0 kg and was less in aganglionic compared to ganglionic tissue. Therefore, weight can be useful to predict RSB diagnostic efficacy.

Skip segment Hirschsprung's disease: report of two rare cases and management

PURPOSE

Skip segment Hirschsprung's disease (SS-HSCR) is defined as the occurrence of a segment of ganglionated intestine surrounded proximally and distally by aganglionosis. The presence of the skip intestinal segment often leads to clinical misdiagnosis, missed diagnosis or inadequate resection of the lesions. The purpose was to describe two new cases of SS-HSCR with the aim of proposing questions regarding the diagnosis and treatment of this rare disease.

METHODS

We reported two cases of infants with SS-HSCR that were admitted to our institution within the last 3 years.

RESULTS

One patient had a skip segment of ganglionated intestine in the ascending colon. In the other patient, there were no ganglionic cells in the rectum and appendix, but ganglionic cells were visible in the proximal ascending colon. The entire colons in the both cases were finally resected, and a pull-through operation was performed.

CONCLUSION

Multipoint biopsy should be performed when the biopsy results are inconsistent with clinical manifestations. Intraoperative laparoscopic identification of the transition zone may be necessary when TCA is suspected. Multisegment biopsy is needed to as a preventative measure for SS-HSCR if TCA is indicated during surgery. Further study is required to determine the optimal length and method of retention of segments.

Current practice of rectal biopsies for the diagnosis of Hirschsprung's disease in Latin America: an international online survey

PURPOSE

The gold standard for the diagnosis of Hirschsprung's disease (HD) is a rectal biopsy. The sample may be obtained using a transanal excisional biopsy (TEB) or suction technique. Rectal suction biopsy (RSB) is not a standard procedure in Latin-America.

AIM

To evaluate the current practice in rectal biopsy for HD among pediatric surgeons.

METHODS

We distributed an online questionnaire among Latin-American pediatric surgeons.

RESULTS

One hundred forty-nine pediatric surgeons from 15 countries completed the anonymous survey (71.4% of Latin-American countries), grouped into 81.9% pediatric surgeons; 8.9% pediatric colorectal surgeons, 8.9% trainees, and 1 pediatric colorectal surgeon fellow. 50.4% reported less than 5 new patients with HD per year, 36.2% 5-10 new cases, and 13.4% more than 10. Only 14.1% of surgeons have access to perform a RSB in the diagnostic work-up of patients with suspected HD, 90% in our study perform an TEB under general anesthesia. When we ask if they could perform both procedures in babies up to 6 months, 52.3% indicate that they prefer an RSB, and for patients older than 6 months, 35.4% favor an RSB. Regarding the number of samples obtained performing an TEB, 30.9% get one biopsy, 29.5% two biopsies, and 39.6% three or more samples. Surgeons obtained the most proximal biopsy at a median of 2.3 cm (range 1-4 cm) above the pectinate line. 67.8% of surgeons prescribed antibiotic prophylaxis. Overall, 16.1% experienced complications, including rectal blood loss (n = 18), and rectal perforation (n = 3). The most frequently used staining methods for rectal biopsies are hematoxylin/eosin (87%), calretinin (56, 8%), and acetylcholinesterase (21.9%).

CONCLUSIONS

In Latin-America, the accessibility for RSB is limited only 18 out of 149 surgeons have access to rectal suction tool. There is no consensus regarding sample number, site of proximal biopsy, and antibiotics use. The complications associated with the procedure seems to be less than reported with RSB. Therefore, we should standardize this common surgical practice and establish universal guidelines for rectal biopsy procedure (RBP).

Clinical predictors of readmission after surgery for Hirschsprung disease

The reasons for readmission of children with Hirschsprung disease (HD) are multiple. The study aims to predict the relevant factors for the readmission of children with HD by collecting and analyzing the relevant data of the child's admission to the hospital at the time of surgery.A retrospective review was performed including all patients with surgical treatment of HD at our institution between the years of 2011 to 2020. Univariate and multivariate Logistic regression analysis were performed to obtain the independent risk factor for this study. The receiver operating characteristic curve (ROC) were used to assess the performance of derived models.A total of 162 patients were identified. The average presurgery weights were 6.93 ± 1.78 kg in the readmission group and 8.38 ± 3.17 kg in the non-readmission group. Six children were classified as a low-weight in the readmission group, and 11 children classified as low-weight in the non-readmission group. The length of the intestinal tube after resection was 25.25 ± 15.21 cm in the readmission group, and 16.23 ± 4.10 cm in the non-readmission group. The ROC for the prediction model of readmission after HD surgery (AUC = 0.811).In children undergoing the HD surgery, we showed preoperative low body weight and long intra-operative bowel resection significantly increase the probability of readmission due to complications.

Associations between common genetic variants in microRNAs and Hirschsprung disease susceptibility in Southern Chinese children

Introduction

Hirschsprung disease (HSCR), characterized by the defective migration of enteric neural crest cells, is a severe congenital tract disease in infants. Its etiology is not clear at present, although a genetic component plays an important role in its etiology. Many studies focused on the polymorphisms of microRNA (miRNA) in several disease progressions have been reported, including HSCR. However, the findings remain inconclusive. The present study aimed to explore the association of genetic variants in miRNAs and HSCR susceptibility in Southern Chinese children.

Methods

Five single nucleotide polymorphisms (SNPs) (miR‐146A rs2910164, miR‐4318 rs8096901, miR‐3142 rs2431697, miR‐3142 rs2431097 and miR‐3142 rs5705329) were included to be genotyped in the stratified analysis through the Mass ARRAY iPLEX Gold system (Sequenom, San Diego, CA, USA) conducted on all the samples, comprising 1470 cases and 1473 controls. After quality control, the minor allele frequency was compared in cases and controls to analyze the association between SNPs and HSCR using PLINK 1.9 (https://www.cog‐genomics.org/plink) and multiple heritability models were tested (additive, recessive and dominant models).

Results

Our results indicated that miR‐4318 rs8096901 polymorphisms were associated with HSCR susceptibility in Southern Chinese children, especially in short‐segment HSCR (S‐HSCR) patients after stratified analysis.

Conclusions

In summary, we report that miR‐4318 rs8096901 was associated with HSCR, especially in SHSCR patients.

Should the search for ganglia in the distal rectal fistula in patients with anorectal malformation be abandoned?

PURPOSE

Occurrence of Hirschsprung's disease in anorectal malformation (ARM) patients is rare, but many surgeons still ask to pathologists to search for ganglia in the terminal rectum/fistula; the histological procedure is time and money consuming and the results confounding. A consecutive series of ARM patients, in which the presence of ganglia in terminal rectum was revised, is herein presented.

MATERIALS AND METHODS

Rectal specimens of ARM patients who underwent corrective surgery in the last 6 years were retrieved. The histological protocol included H&E staining and calretinin immunohistochemistry. Each specimen is processed until all material is examined if no ganglia are retrieved after the first twelve sections.

RESULTS

Forty cases were examined. Eight patients were younger than 1 month of age at operation. The mean length of the specimen was 1.5cm (range: 1-3 cm). Upon clinical request, ganglia were searched in 15/40 cases (37.5%) and resulted absent in 10/15 (66.5%). All patients have been followed and none developed signs or symptoms suggestive for Hirschsprung.

CONCLUSIONS

The practice to search for ganglia in the terminal rectum/fistula in ARM patients should be abandoned, as incidence of associated colorectal diseases is rare. Moreover, the procedure is expensive both in terms of laboratory's reagents and working time of expert pathologists and technicians.

LEVEL OF EVIDENCE

Level IV (Case Series with no Comparison Group).

Large intestine embryogenesis: Molecular pathways and related disorders (Review)

The large intestine, part of the gastrointestinal tract (GI), is composed of all three germ layers, namely the endoderm, the mesoderm and the ectoderm, forming the epithelium, the smooth muscle layers and the enteric nervous system, respectively. Since gastrulation, these layers develop simultaneously during embryogenesis, signaling to each other continuously until adult age. Two invaginations, the anterior intestinal portal (AIP) and the caudal/posterior intestinal portal (CIP), elongate and fuse, creating the primitive gut tube, which is then patterned along the antero‑posterior (AP) axis and the radial (RAD) axis in the context of left‑right (LR) asymmetry. These events lead to the formation of three distinct regions, the foregut, midgut and hindgut. All the above‑mentioned phenomena are under strict control from various molecular pathways, which are critical for the normal intestinal development and function. Specifically, the intestinal epithelium constitutes a constantly developing tissue, deriving from the progenitor stem cells at the bottom of the intestinal crypt. Epithelial differentiation strongly depends on the crosstalk with the adjacent mesoderm. Major molecular pathways that are implicated in the embryogenesis of the large intestine include the canonical and non‑canonical wingless‑related integration site (Wnt), bone morphogenetic protein (BMP), Notch and hedgehog systems. The aberrant regulation of these pathways inevitably leads to several intestinal malformation syndromes, such as atresia, stenosis, or agangliosis. Novel theories, involving the regulation and homeostasis of intestinal stem cells, suggest an embryological basis for the pathogenesis of colorectal cancer (CRC). Thus, the present review article summarizes the diverse roles of these molecular factors in intestinal embryogenesis and related disorders.

Usefulness of Delayed Films of Contrast Enema for Detecting Hirschsprung's Disease

Background

Contrast enema (CE) in Hirschsprung’s disease (HD) provides a road map to surgeons by ascertaining the transition zone (TZ) and helps in pre-surgical planning. In our institute, we use CE as the initial investigation for HD and carry on till the whole colon is fully distended, followed by a 24-hour abdominal film which is also a part of the international protocol. The main aim of this study was to evaluate the usefulness of this 24-hour delayed film in detecting HD, compare it with gold-standard biopsy results, and to evaluate other imaging features of contrast enema for diagnosis of HD in our tertiary-care hospital in Pakistan. 

Methods

This retrospective study was conducted at the Department of Radiology, Aga Khan University Hospital, Karachi. Records of pediatric patients referred for radiological evaluation of symptoms and signs suspicious of HD during the years 2007-2017 were reviewed. A delayed film was labeled positive if the contrast was not completely evacuated when the residual contrast was present till transverse colon and not beyond. Specificity and sensitivity along with positive and negative predictive values were calculated for each finding according to rectal biopsy, taken as the gold standard.

Results

In all, 82 patients met the inclusion criteria out of 111 cases, as they had both biopsy results and delayed 24-hour films. HD was confirmed using rectal biopsy in 56 (43 patients were males and 13 were females) of 82 cases. The most sensitive radiological finding was the transition zone with a sensitivity of 91.07%. The rectosigmoid index was the second most common finding on contrast enema with a sensitivity and specificity of 91.07% and 83.93%, respectively. In all, 59% patients had a positive delayed 24-hour film and were confirmed with having HD on biopsy. The sensitivity, specificity, and positive predictive value of delay in contrast evacuation after 24 hours in our study was 81.25%, 90.91%, and 97.50% respectively.

Conclusion

Contrast enema examinations along with the 24-hour delayed film with mid transverse colon cut-off are optimal for initially investigating HD in a developing nation, and our results show that it correlates well with biopsy. However, rectal biopsy still remains the gold standard for diagnosis. 

Expression of BMP-4 and Smad1 in patients with Hirschsprung disease and its clinical significance

Expression and clinical significance of bone morphogenetic protein (BMP)-4 and Smad1 in patients with Hirschsprung disease (HD) were investigated. A retrospective analysis of 96 HD patients (experimental group) admitted to Xuzhou Children's Hospital, Xuzhou Medical University from June 2015 to June 2017 was performed. According to the samples, the experimental group was divided into the stenosis group, the transition group and the expansion group. Forty-seven children with colostomy due to intestinal obstruction were selected as the control group. The expression levels of BMP-4 and Smad1 proteins were detected by immunohistochemical staining. The expression levels of BMP-4 and Smad mRNA were detected by real-time quantitative PCR (RT-qPCR), and were quantified and compared. Via immunohistochemistry, BMP-4 and Smad1 proteins were detected in the samples of different parts of HD patients and children with intestinal obstruction. The positive expression levels of BMP-4 and Smad1 proteins in the transition group were decreased compared with those in the expansion and control groups (P<0.05), and the positive expression levels of BMP-4 and Smad1 proteins in the stenosis group were decreased compared with those in the transition, expansion, and control groups (P<0.05). Also, the gene expression levels of BMP-4 and Smad1 in the transition and stenosis groups were successively decreased, and the differences were statistically significant (P<0.05). In conclusion, the expression of BMP-4 and Smad1 in the intestinal plexus of HD lesions was significantly reduced, indicating that BMP-4 and Smad1 are closely related to the occurrence of HD, and it is suspected that they have a certain influence on the intestinal development of congenital digestive tract malformations.

Error traps and culture of safety in Hirschsprung disease

Hirschsprung disease affects many children every year around the world. Currently, there is an extensive menu of diagnostic methods, and surgical treatments. This situation compels the physicians to follow the rationale of these interventions. The comprehensive diagnosis and treatment of Hirschsprung disease need singular procedures. The clear understanding of how to perform each of these techniques, as well as to read the results is mandatory. Otherwise, the medical team may perform unconscious errors and fall into traps. Many errors still happen in patients with Hirschsprung, resulting in a spectrum of problems; from delayed diagnosis to unnecessary colectomies. In other patients, the damage to the anal canal results in fecal incontinence. When this is established, it is an unreversed and devastating social problem. This article describes why these errors occur and how to prevent them.

The role of mast cells in pediatric gastrointestinal disease

Mast cells are granulocytes derived from CD34+ pluripotent progenitor cells that demonstrate plasticity in their development, leaving the bone marrow and differentiating in the tissue where they ultimately reside. They are best known for their role in the allergic response, but also play a prominent immunoregulatory role in other processes, including immune tolerance, the innate immune response, angiogenesis, wound healing and tissue remodeling. Mast cells are found throughout the gastrointestinal tract; their metabolic products influence and regulate intestinal epithelial and endothelial function, gastrointestinal secretion, intestinal motility and absorption, and contribute to host defense. They also play an important role in the development of visceral hypersensitivity through bidirectional interaction with the enteric nervous system. Mast cells have been found to have an increasingly important role in the pathophysiology of a number of pediatric gastrointestinal diseases. This review summarizes the current understanding of the role that mast cells play in the development of pediatric gastrointestinal disorders, including eosinophilic esophagitis, functional dyspepsia, irritable bowel syndrome, celiac disease, inflammatory bowel disease, histologically negative appendicitis, Hirschsprung’s disease, intestinal neuronal dysplasia, and food protein-induced enterocolitis syndrome.

Gfra1 Underexpression Causes Hirschsprung's Disease and Associated Enterocolitis in Mice

BACKGROUND & AIMS

RET, the receptor for the glial cell line-derived neurotrophic factor (GDNF) family ligands, is the most frequently mutated gene in congenital aganglionic megacolon or Hirschsprung's disease (HSCR). The leading cause of mortality in HSCR is HSCR-associated enterocolitis (HAEC), which is characterized by altered mucin composition, mucin retention, bacterial adhesion to enterocytes, and epithelial damage, although the order of these events is obscure. In mice, loss of GDNF signaling leads to a severely underdeveloped enteric nervous system and neonatally fatal kidney agenesis, thereby precluding the use of these mice for modeling postnatal HSCR and HAEC. Our aim was to generate a postnatally viable mouse model for HSCR/HAEC and analyze HAEC etiology.

METHODS

GDNF family receptor alpha-1 (GFRa1) hypomorphic mice were generated by placing a selectable marker gene in the sixth intron of the Gfra1 locus using gene targeting in mouse embryonic stem cells.

RESULTS

We report that 70%-80% reduction in GDNF co-receptor GFRa1 expression levels in mice results in HSCR and HAEC, leading to death within the first 25 postnatal days. These mice mirror the disease progression and histopathologic findings in children with untreated HSCR/HAEC.

CONCLUSIONS

In GFRa1 hypomorphic mice, HAEC proceeds from goblet cell dysplasia, with abnormal mucin production and retention, to epithelial damage. Microbial enterocyte adherence and tissue invasion are late events and therefore unlikely to be the primary cause of HAEC. These results suggest that goblet cells may be a potential target for preventative treatment and that reduced expression of GFRa1 may contribute to HSCR susceptibility.

Diagnosis of Hirschsprung's disease in children: Preliminary evaluation of a novel endoscopic technique for rectal biopsy

Background and Aim

The diagnosis of Hirschsprung's disease (HD) relies on anorectal manometry and rectal biopsy. The role of endoscopic biopsy is uncertain for the diagnosis of HD in children. In this study, we evaluated the adequacy of biopsies procured by endoscopic mucosal resection (EMR) for the diagnosis of HD.

Methods

Consecutive children with suspected HD from January 2013 to January 2018 were enrolled in the study. EMR was performed using the standard band ligation device at a distance of about 3 cm from dentate line in rectum. All samples were assessed macroscopically and microscopically. An adequate sample was defined as those measuring >3 mm and including adequate submucosa.

Results

A total of 132 children underwent evaluation for constipation in the study period. Of these, 10 children (median age, 4.25 years) underwent EMR using the band ligation device for the evaluation of HD. EMR was performed with and without submucosal lifting injection in four and six children, respectively. All the samples were adequate macroscopically (>3 mm). Absence of ganglion cells was noted in six children. Of these, three children underwent full‐thickness rectal biopsy followed by surgery. Three children did not undergo surgery. Ganglion cells were identified in four children, thereby excluding the diagnosis of HD.

Conclusion

Rectal biopsy using EMR with a band ligation device is feasible, safe, and provides adequate sample for the evaluation of HD in children.

Diagnostic Accuracy of Combined Acetylcholinesterase Histochemistry and Calretinin Immunohistochemistry of Rectal Biopsy Specimens in Hirschsprung's Disease

BACKGROUND

Acetylcholinesterase (AchE) histochemistry has been established as an accurate diagnostic tool for Hirschsprung's disease (HD). In addition, calretinin immunohistochemistry is also reported as a reliable and adjunctive method to diagnose HD. We investigated the diagnostic value of combined AchE histochemistry and calretinin immunohistochemistry in rectal suction biopsies from HD and non-HD patients.

METHODS

We retrospectively reviewed 99 rectal suction biopsy specimens including 4 repeat biopsies from 95 patients (34 HD and 61 non-HD). Each specimen was evaluated with hematoxylin-eosin, AchE histochemistry, and calretinin immunohistochemistry.

RESULTS

Of 95 patients, only 21 (22.1%) showed some ganglion cells. All 61 non-HD cases revealed no abnormal AchE-positive fibers. Of 34 HD patients, 32 exhibited abnormal AchE fibers, but 2 showed no stained fibers. None of the tissues from the HD patients exhibited calretinin immunoreactivity. Test sensitivity and specificity of AchE histochemistry alone were 93.5% and 100.0%, respectively, while calretinin immunohistochemistry were 100.0% and 85.2%, respectively.

CONCLUSIONS

AchE histochemistry is a good diagnostic method for HD, if feasible, and a combination of AchE histochemistry and calretinin immunohistochemistry will help increase the accuracy of the diagnosis of HD.

Ganglion Cells Are Frequently Present in Pediatric Mucosal Colorectal Biopsies: H&E Sections and Calretinin Immunohistochemistry in the Evaluation of Children With Chronic Constipation

Hirschsprung disease (HD) rarely presents as chronic constipation after the newborn period. At our institution, calretinin immunohistochemistry (CAL) is frequently requested by clinicians on rectal mucosal biopsies (RMBs) taken during colonoscopy in older children in whom suspicion for HD is low. We hypothesized that review of these biopsies would frequently reveal ganglion cells (GCs). We reviewed features of mucosal biopsies (November 2013 to September 2015) from children ≥1 year of age on which clinicians had requested CAL on at least one specimen. A total of 93 biopsies with paired CAL from 83 patients were suitable for study (ages 1-18 years, M:F 1.2). Submitted clinical indication was constipation in 62 patients (75%). GCs were found within or subjacent to muscularis mucosa in 63 biopsies (68%), 12 (19%) of which were designated from a specific anatomic site, eg, 2 or 3 cm. In 25 of 63 (40%) cases, GCs were identified on one of the first 3 sections (median 5th, range 1st-54th). Forty-six cases (73%) contained no or <0.5 mm of submucosa (SM, range 0-2 mm). All but one case (62/63, 98%) with identified GCs showed positive CAL staining; a single case showed equivocal staining. Among the 30 biopsies with no observed GCs, none (0%) had >1 mm of SM, and 21 (70%) had no SM. CAL was positive in 28 (93%) and equivocal/weak in 2 (7%); no additional work-up for HD was pursued. The data suggest that H&E sections of RMBs can exclude HD at a specified site in many cases and provide the basis for a future study examining the utility of CAL in RMBs without SM as a means for excluding HD.

Is hematoxylin-eosin staining in rectal mucosal and submucosal biopsies still useful for the diagnosis of Hirschsprung disease?

Background

Hematoxylin-eosin (HE) staining of a full-thickness rectal wall fragment is classically used for the diagnosis of Hirschsprung disease (HD). However, this technique requires large fragments for a better diagnosis. Additionally, the histochemical and immunohistochemical methods of staining small fragments of rectal mucosal and submucosal biopsies are not available in all centers. Therefore, the possibility of diagnosing HD through HE staining in these biopsies could be a valuable alternative for centers that do not have more specific techniques. The objectives of the current investigation were to evaluate the concordance of the results obtained by HE staining and the calretinin method with acetylcholinesterase (AChE) activity in fragments of mucosa and submucosa in the diagnosis of HD.

Methods

For this study, 50 cases from our laboratory were selected. The tissue material was embedded in paraffin. Sixty levels of each fragment were utilized for HE, and the other 3 levels were used for calretinin. These slides were analyzed under the microscope, photographed and classified as either positive for HD when no ganglion cells were found with nerve trunks present or as negative when ganglion cells were found. The results from reading the slides were compared with those of AChE.

Results

Of the 50 cases evaluated by the HE technique, only 5 contradicted the diagnosis based on AChE, with a Kappa value of 0.800 and an accuracy of 90%. In the comparison between calretinin and AChE, 8 cases were discordant, with a Kappa value of 0.676 and an accuracy of 84%.

Conclusions

The concordance of results from AChE and HE methods was satisfactory, allowing for the potential use of the HE method for fragments of mucosa and submucosa as a valid alternative in the diagnosis of HD. The immunohistochemical technique of calretinin did not show good agreement with the AChE activity in our study.

Preliminary identification of key miRNAs, signaling pathways, and genes associated with Hirschsprung's disease by analysis of tissue microRNA expression profiles

BACKGROUND

Hirschsprung's disease (HSCR) is a congenital gut motility disorder of infants, and if left untreated, it is fatal to the affected infants. This study aimed to identify key microRNAs (miRNAs), signaling pathways and genes involved in the pathogenesis of HSCR.

METHODS

The miRNA microarray dataset GSE77296 was downloaded. Nine colon tissue samples were available: six from HSCR patients and three matched control samples. Differentially expressed miRNAs (DEMs) were identified after data preprocessing. Target genes of the selected upregulated and downregulated DEMs were predicted. In addition, functional enrichment analyses for the selected DEMs and target genes were conducted. Finally, interaction networks between the DEMs and target genes were constructed.

RESULTS

A total of 162 DEMs (73 upregulated and 89 downregulated) were obtained. A total of 2511 DEM-target gene pairs for the 40 selected DEMs were identified, including 1645 pairs for the upregulated DEMs and 866 pairs for the downregulated DEMs. The upregulated DEM miR-141-3p and down-regulated DEM miR-30a-3p were identified as key miRNAs by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and network analyses. Besides, KEGG pathway enrichment analysis revealed that pathways in cancer and the mitogen-activated protein kinase (MAPK) signaling pathway were key pathways. The key genes frizzled class receptor 3 (FZD3) and docking protein 6 (DOK6) were obtained through the DEM-target gene interaction networks.

CONCLUSION

Two key miRNAs (miR-141-3p and miR-30a-3p), the MAPK signaling pathway and two key genes (FZD3 and DOK6) were implicated in the pathogenesis of HSCR.

Utility of Peripherin Versus MAP-2 and Calretinin in the Evaluation of Hirschsprung Disease

Hirschsprung disease (HD) is a congenital malformation resulting from the lack of migration of ganglion cells in the colon. The absence of ganglion cells in rectal suction biopsies aids in diagnosis, but evaluation of these small biopsies can be difficult. In this study, we compare the microtubule-associated protein-2 (MAP-2), calretinin, and peripherin immunohistochemical stains in 237 selected biopsies performed to rule out HD. By H&E stain, a total of 78 biopsies had ganglion cells, whereas 83 biopsies had no ganglion cells, and an additional 76 biopsies were equivocal for ganglion cells. Of the 78 biopsies with ganglion cells, MAP-2 was positive in 73 (94%), calretinin in 76 (97%), and peripherin in 78 (100%). Of the 83 biopsies with no ganglion cells, calretinin and peripherin highlighted nerve fibrils and ganglion cells, respectively, in 3 biopsies, whereas MAP-2 was positive in only 1 biopsy. Of the 76 biopsies equivocal for ganglion cells, 16 cases were positive by all 3 stains, an additional case by both calretinin and peripherin, and 2 cases by peripherin only. All of the newly positive biopsies were from patients without HD. This study demonstrates that peripherin is superior in helping to rule out HD in these small biopsies, highlighting ganglion cells in virtually all cases with ganglion cells, whereas MAP-2 and calretinin are less sensitive for identification of ganglion cells and nerve fibrils, respectively. In patients with HD, a panel using calretinin and peripherin with or without MAP-2 may be most helpful in identifying transition zones.

Rectal Suction Biopsy in Patients With Previous Anorectal Surgery for Hirschsprung Disease

OBJECTIVES

The aim of the study was to determine rates of histologically positive, negative, and inconclusive rectal suction biopsies in post-pull-through patients with Hirschsprung disease evaluated for potential residual aganglionosis at our institution and to determine how patients were managed after a post-pull-through rectal suction biopsy.

METHODS

Thirty-nine post-pull-through suction biopsies from our institution were reviewed. Samples, stained with H&E and often acetylcholinesterase and/or calretinin, were categorized as "histologically" positive, negative, or inconclusive for aganglionosis. Subsequent clinical action was categorized as bowel resection, no further procedure, or rebiopsy. Agreement between histologic diagnosis and clinical action was assessed.

RESULTS

Histologically, all biopsies were inconclusive (46%) or negative (54%) for residual aganglionosis. Postbiopsy clinical action included redo pull-through (5%), no further procedure (59%), or rebiopsy (36%). Rebiopsy was sought in 2 of 21 histologically negative patients and in only 12 of 18 histologically indeterminate patients. Eventual redo pull-through procedures in 6 of 39 patients showed 4 with residual aganglionosis and 2 with abnormalities suggesting residual "transition zone."

CONCLUSIONS

Our findings show that suction biopsy after pull-through was frequently histologically indeterminate and never definitively positive for residual aganglionosis. When biopsy was histologically indeterminate, rebiopsy was pursued less commonly than may be expected. Our findings emphasize that suction biopsy examination is not a "criterion standard" for residual aganglionosis, but instead a component of a diagnosis that ultimately combines clinicopathologic factors, the constellation of which can sometimes spare patients from a more invasive full-thickness biopsy.

Defining the transcriptomic landscape of the developing enteric nervous system and its cellular environment

BACKGROUND

Motility and the coordination of moving food through the gastrointestinal tract rely on a complex network of neurons known as the enteric nervous system (ENS). Despite its critical function, many of the molecular mechanisms that direct the development of the ENS and the elaboration of neural network connections remain unknown. The goal of this study was to transcriptionally identify molecular pathways and candidate genes that drive specification, differentiation and the neural circuitry of specific neural progenitors, the phox2b expressing ENS cell lineage, during normal enteric nervous system development. Because ENS development is tightly linked to its environment, the transcriptional landscape of the cellular environment of the intestine was also analyzed.

RESULTS

Thousands of zebrafish intestines were manually dissected from a transgenic line expressing green fluorescent protein under the phox2b regulatory elements [Tg(phox2b:EGFP) ^w37 ]. Fluorescence-activated cell sorting was used to separate GFP-positive phox2b expressing ENS progenitor and derivatives from GFP-negative intestinal cells. RNA-seq was performed to obtain accurate, reproducible transcriptional profiles and the unbiased detection of low level transcripts. Analysis revealed genes and pathways that may function in ENS cell determination, genes that may be identifiers of different ENS subtypes, and genes that define the non-neural cellular microenvironment of the ENS. Differential expression analysis between the two cell populations revealed the expected neuronal nature of the phox2b expressing lineage including the enrichment for genes required for neurogenesis and synaptogenesis, and identified many novel genes not previously associated with ENS development. Pathway analysis pointed to a high level of G-protein coupled pathway activation, and identified novel roles for candidate pathways such as the Nogo/Reticulon axon guidance pathway in ENS development.

CONCLUSION

We report the comprehensive gene expression profiles of a lineage-specific population of enteric progenitors, their derivatives, and their microenvironment during normal enteric nervous system development. Our results confirm previously implicated genes and pathways required for ENS development, and also identify scores of novel candidate genes and pathways. Thus, our dataset suggests various potential mechanisms that drive ENS development facilitating characterization and discovery of novel therapeutic strategies to improve gastrointestinal disorders.

Advances in understanding functional variations in the Hirschsprung disease spectrum (variant Hirschsprung disease)

Hirschsprung disease (HSCR) is a fairly well understood congenital, genetically based functional obstruction due to the congenital absence of ganglion cells in the distal bowel. However, although over 90% of Hirschsprung cases conform to the normally accepted histological diagnostic criteria, it has become increasingly clear that in addition to HSCR, there is a group of functional disturbances relating to a number of other congenital neurodysplastic conditions causing some degree of gastrointestinal tract malfunction. Although these represent a variety of possibly separate conditions of the enteric nervous system, this spectrum it would appear to be also influenced by similar developmental processes. The term "variant Hirschsprung" is commonly used to describe these conditions, but ganglion cells are mostly present if abnormal in number and distribution. These conditions are a problem group being amongst the most difficult to diagnose and treat with possible practical and legal consequences. The problem appears to be possibly one of definition which has proven difficult in the relative paucity of normal values, especially when correlated to age and gestation. It is the purpose of this paper to review the current position on these conditions and to explore possible shared common pathogenetic and genetic mechanisms. This article explores those conditions where a similar pathogenetic mechanisms to HSCR can be demonstrated (e.g. hypoganglionosis) as well as other neural features, which appear to represent separate conditions possibly linked to certain syndromes.

The evaluation of rectal mucosal punch biopsy in the diagnosis of Hirschsprung's disease: a 30-year experience of 954 patients

PURPOSE

For 30 years, we have consecutively performed rectal mucosal punch biopsy to diagnose Hirschsprung's disease. The aim of this study was to evaluate the safety of our technique.

METHODS

Patients with suspected Hirschsprung's disease who underwent punch biopsy, including our original "K-PUNCH" method using an S-moid forceps and non-specific blood-collecting tube at our department and branch hospital between April 1986 and March 2016 were included in the present study. Our punch biopsy technique is characterized by excellent visibility and a direct grasping sensation. The backgrounds and complications of the patients were retrospectively investigated.

RESULTS

During this period, 954 patients (median age 4 months; range 1 day-73 years) underwent punch biopsy. Although there were no cases of severe complications (i.e., rectal perforation, infection or full-thickness biopsy), one (0.1%) of the 954 cases in the early period showed liver dysfunction and required transfusion due to bleeding. In addition, inappropriate specimens were obtained in 37 patients (3.9%).

CONCLUSION

Punch biopsy including the "K-PUNCH" method is considered safe and feasible and is associated with a low rate of complications and inappropriate specimen harvesting among patients of all ages. Comorbidities, including the potential for hemorrhage, should always be considered.

Enteric nervous system development: A crest cell's journey from neural tube to colon

The enteric nervous system (ENS) is comprised of a network of neurons and glial cells that are responsible for coordinating many aspects of gastrointestinal (GI) function. These cells arise from the neural crest, migrate to the gut, and then continue their journey to colonize the entire length of the GI tract. Our understanding of the molecular and cellular events that regulate these processes has advanced significantly over the past several decades, in large part facilitated by the use of rodents, avians, and zebrafish as model systems to dissect the signals and pathways involved. These studies have highlighted the highly dynamic nature of ENS development and the importance of carefully balancing migration, proliferation, and differentiation of enteric neural crest-derived cells (ENCCs). Proliferation, in particular, is critically important as it drives cell density and speed of migration, both of which are important for ensuring complete colonization of the gut. However, proliferation must be tempered by differentiation among cells that have reached their final destination and are ready to send axonal extensions, connect to effector cells, and begin to produce neurotransmitters or other signals. Abnormalities in the normal processes guiding ENCC development can lead to failure of ENS formation, as occurs in Hirschsprung disease, in which the distal intestine remains aganglionic. This review summarizes our current understanding of the factors involved in early development of the ENS and discusses areas in need of further investigation.

A Novel Zebrafish ret Heterozygous Model of Hirschsprung Disease Identifies a Functional Role for mapk10 as a Modifier of Enteric Nervous System Phenotype Severity

Hirschsprung disease (HSCR) is characterized by absence of enteric neurons from the distal colon and severe intestinal dysmotility. To understand the pathophysiology and genetics of HSCR we developed a unique zebrafish model that allows combined genetic, developmental and in vivo physiological studies. We show that ret mutant zebrafish exhibit cellular, physiological and genetic features of HSCR, including absence of intestinal neurons, reduced peristalsis, and varying phenotype expressivity in the heterozygous state. We perform live imaging experiments using a UAS-GAL4 binary genetic system to drive fluorescent protein expression in ENS progenitors. We demonstrate that ENS progenitors migrate at reduced speed in ret heterozygous embryos, without changes in proliferation or survival, establishing this as a principal pathogenic mechanism for distal aganglionosis. We show, using live imaging of actual intestinal movements, that intestinal motility is severely compromised in ret mutants, and partially impaired in ret heterozygous larvae, and establish a clear correlation between neuron position and organised intestinal motility. We exploited the partially penetrant ret heterozygous phenotype as a sensitised background to test the influence of a candidate modifier gene. We generated mapk10 loss-of-function mutants, which show reduced numbers of enteric neurons. Significantly, we show that introduction of mapk10 mutations into ret heterozygotes enhanced the ENS deficit, supporting MAPK10 as a HSCR susceptibility locus. Our studies demonstrate that ret heterozygous zebrafish is a sensitized model, with many significant advantages over existing murine models, to explore the pathophysiology and complex genetics of HSCR.

Hirschsprung Disease (HSCR) is a common congenital intestinal motility disorder diagnosed at birth by absence of enteric neurons in the distal gut, leading to intestinal obstruction that requires life-saving surgery. HSCR exhibits complex inheritance patterns and its genetic basis is not fully understood. Although well studied by human geneticists, and modelled using mouse, significant questions remain about the cellular and genetic causes of the disease and the relationship between neuron loss and defective intestinal motility. Here we use accessible, transparent zebrafish to address these outstanding questions. We establish that ret mutant zebrafish display key features of HSCR, including absence of intestinal neurons, reduced gut motility and varying phenotype expressivity. Using live imaging, possible in zebrafish but not in mouse, we demonstrate that decreased migration speed of enteric neuron progenitors colonising the gut is the principal defect leading to neuron deficits. By direct examination of gut motility in zebrafish larvae, we establish a clear correlation between neurons and motility patterns. Finally, we show that mapk10 mutations worsen the enteric neuron deficit of ret mutants, indicating that mutations in MAPK10 may increase susceptibility to HSCR. We show many benefits of modelling human genetic diseases in zebrafish and advance our understanding of HSCR.

Current practice patterns of rectal suction biopsy in the diagnostic work-up of Hirschsprung's disease: results from an international survey

PURPOSE

The diagnosis of Hirschsprung's disease (HD) was revolutionized by the introduction of rectal suction biopsy (RSB), allowing specimens to be taken without general anesthesia on the ward or as an out-patient procedure. However, insufficient tissue samples are not uncommon, and subsequently histopathologists often remain reluctant to confirm the presence or absence of enteric ganglion cells merely on the basis of submucosal RSBs. The aim of this study was to evaluate the current usage of RSB in the diagnostic work-up of HD based on an international survey.

METHODS

A 15-item questionnaire was distributed among participants and faculty members at the 21st International Meeting of the Pediatric Colorectal Society.

RESULTS

Eighty-seven pediatric surgeons from 30 countries completed the anonymous survey (response rate 70.2 %), grouped into 68 (78.2 %) staff surgeons and 19 (21.8 %) trainees, with a median work experience of 18 years (range 2-45 years). Of these, 74 (85.1 %) use RSB in the diagnostic work-up of patients with suspected HD, whereas 13 (14.9 %) prefer open full-thickness biopsy under general anesthesia. In total, 47 (63.5 %) respondents perform ≥20 RSBs (range 3-100 RSBs) per year. Five different RSB instruments were reported, the most common ones being rbi2 (65.0 %), Solo-RBT (15.0 %) and multipurpose suction biopsy kit (8.3 %). Only 22 (29.7 %) of the respondents use a defined negative suction pressure, with a median of 10 mL air (range 6-25 mL air). The most proximal reported biopsy site was located at a median of 2 cm (range 1-15 cm) above the pectinate line and a median of 2 (range 1-5) specimens are routinely taken, mainly from the posterior rectal wall. Insufficient tissue samples with need for repeat RSB were encountered in a median of 10 % (range 0-40 %). Most frequently used staining methods for rectal biopsies are hematoxylin/eosin (75.9 %), acetylcholinesterase (73.6 %), and calretinin (33.3 %). Overall, 36 (48.6 %) respondents had experienced RSB-related complications, including self-limiting rectal blood loss (n = 28), persistent rectal bleeding requiring blood transfusion (n = 9) and rectal perforation requiring surgical intervention (n = 7).

CONCLUSIONS

Although RSB is considered to be today's gold standard for the diagnosis of HD, many aspects of its current usage are lacking consensus. Therefore, a prospective multi-center study or larger global audit appears warranted to identify if the present survey reflects common surgical practice and to establish universal standards for RSB.

A Novel Mutation in Nucleoporin 35 Causes Murine Degenerative Colonic Smooth Muscle Myopathy

Chronic intestinal pseudo-obstruction (CIPO) is a rare but life-threatening disease characterized by severe intestinal dysmotility. Histopathologic studies in CIPO patients have identified several different mechanisms that appear to be involved in the dysmotility, including defects in neurons, smooth muscle, or interstitial cells of Cajal. Currently there are few mouse models of the various forms of CIPO. We generated a mouse with a point mutation in the RNA recognition motif of the Nup35 gene, which encodes a component of the nuclear pore complex. Nup35 mutants developed a severe megacolon and exhibited a reduced lifespan. Histopathologic examination revealed a degenerative myopathy that developed after birth and specifically affected smooth muscle in the colon; smooth muscle in the small bowel and the bladder were not affected. Furthermore, no defects were found in enteric neurons or interstitial cells of Cajal. Nup35 mice are likely to be a valuable model for the subtype of CIPO characterized by degenerative myopathy. Our study also raises the possibility that Nup35 polymorphisms could contribute to some cases of CIPO.

Enteric nervous system assembly: Functional integration within the developing gut

Co-ordinated gastrointestinal function is the result of integrated communication between the enteric nervous system (ENS) and "effector" cells in the gastrointestinal tract. Unlike smooth muscle cells, interstitial cells, and the vast majority of cell types residing in the mucosa, enteric neurons and glia are not generated within the gut. Instead, they arise from neural crest cells that migrate into and colonise the developing gastrointestinal tract. Although they are "later" arrivals into the developing gut, enteric neural crest-derived cells (ENCCs) respond to many of the same secreted signalling molecules as the "resident" epithelial and mesenchymal cells, and several factors that control the development of smooth muscle cells, interstitial cells and epithelial cells also regulate ENCCs. Much progress has been made towards understanding the migration of ENCCs along the gastrointestinal tract and their differentiation into neurons and glia. However, our understanding of how enteric neurons begin to communicate with each other and extend their neurites out of the developing plexus layers to innervate the various cell types lining the concentric layers of the gastrointestinal tract is only beginning. It is critical for postpartum survival that the gastrointestinal tract and its enteric circuitry are sufficiently mature to cope with the influx of nutrients and their absorption that occurs shortly after birth. Subsequently, colonisation of the gut by immune cells and microbiota during postnatal development has an important impact that determines the ultimate outline of the intrinsic neural networks of the gut. In this review, we describe the integrated development of the ENS and its target cells.

Rectal biopsy for Hirschsprung's disease: a review of techniques, pathology, and complications

BACKGROUND

Hirschsprung's disease (HD) is one of the most common congenital anomalies of colorectal function, affecting approximately 1 in 5000 live births, with a 4:1 male predominance. HD is characterized by aganglionosis that is most often limited to the rectosigmoid, but can extend proximally along the colon and, in rare instances, reach into the small intestine. A clinical history of delayed passage of meconium beyond 48 hours after birth, physical exam findings of abdominal distention and vomiting, and a contrast enema demonstrating a transition zone are highly suggestive of HD.

DATA SOURCES

We searched databases including PubMed, Google Scholar, and Scopus for the following key words: Hirschsprung's disease, rectal biopsy, pathology, ganglion cell, nerve trunk hypertrophy, pediatric constipation, and selected publications written in English that were relevant to the scope of this review.

RESULTS

Based on the data presented in the literature, we reviewed 1) biopsy techniques for the diagnosis of Hirschsprung's disease, addressed inadequate biopsies, and complications from rectal biopsy, and 2) pathologic and histologic interpretation of biopsy specimens for the diagnosis of Hirschsprung's disease.

CONCLUSION

A well-executed rectal biopsy with expert pathologic evaluation of the specimen remains the gold standard for the diagnosis of Hirschsprung's disease and is the subject of this review.

Aganglionosis with the absence of hypertrophied nerve fibres predicts disease proximal to rectosigmoid colon

PURPOSE

The gold standard for the diagnosis of Hirschsprung's disease (HSCR) is the pathologic evaluation of a rectal biopsy that demonstrates the absence of ganglion cells and nerve fibre hypertrophy. However, it has been frequently reported that hypertrophic nerves may not be present in some variants like long-segment HSCR, total colonic aganglionosis, premature and very young infants. The aim of this study was to determine this association.

METHODS

We performed a retrospective review of the HSCR database at our tertiary care children's hospital from 2000 to 2013. In order to analyse the relationship between the diameter of the nerve fibres and the level of aganglionosis, we classified the patient sample into two groups-fibres ≤40 and >40 μm. The groups were statistically compared with P < 0.05 being significant.

RESULTS

Rectal biopsies of 92 patients confirmed as HSCR with definitive operation performed at the same institution were reviewed. The mean nerve diameter was 50.1 μm (range 20-87.5 μm). Nerve fibre diameter ≤40 μm was predictive of transition zone above the sigmoid colon. A specificity of 77.3 % and a likelihood ratio of 2.03 supported this perception. No correlation was noted between nerve fibre diameter and gestational age at birth, birth weight or age at biopsy.

CONCLUSION

The absence of nerve fibre hypertrophy in the presence of aganglionosis on rectal biopsy specimens is predictive of long-segment HSCR.

Infant's Age Influences the Accuracy of Rectal Suction Biopsies for Diagnosing of Hirschsprung's Disease

BACKGROUND & AIMS

Hirschsprung's disease (HD) is a rare birth defect of the distal colon. Analysis of rectal suction biopsy (RSB) is considered to be the most reliable method for its diagnosis in infants. However, the diagnostic accuracy of RSB analysis could be affected by the patient's age, possibly because of rapid development of the enteric nervous system in the first weeks after birth. Because there is a trend toward testing for HD at early ages, we aimed to determine whether the diagnostic accuracy of RSB analysis is associated with the patient's age.

METHODS

We performed a retrospective analysis of all patients from whom 1 or more RSBs were analyzed from 1975 through 2011 (529 RSBs from 441 patients). Outcomes of RSB analyses were categorized as positive, inconclusive, or negative for HD. Primary diagnoses, based only on RSB, were compared with final diagnoses made after at least 1 year of clinical follow-up. Age at time of RSB analysis was corrected for the gestational age. By using these criteria, we determined the diagnostic accuracy of RSB analysis for different age groups.

RESULTS

RSB analysis identified HD in patients with sensitivity values of 46% (patients -45 to 7 days old), 47% (8-22 days old), and 62% (23-39 days old) (corrected for gestational age). The average sensitivity with which RSB analysis identified HD in patients older than 39 days was 88%. RSB identified HD in patients younger than 39 days old with significantly lower sensitivity than in older patients (50% vs 88%, P < .001). The specificity with which RSB identified infants without HD was not affected by age (average 95%). Of all RSBs, 11% were inconclusive for the diagnosis of HD.

CONCLUSIONS

RSB analysis identifies HD in patients younger than 39 days old with only 50% sensitivity. Moreover, RSBs obtained from younger patients often lead to inconclusive outcomes and require additional biopsies. We propose that for infants suspected of HD at these ages, a noninvasive technique, such as anorectal manometry, should be used for a primary diagnosis. RSB should thereafter be used to confirm the diagnosis when the infant is older than 39 days.

Isolation of Enteric Nervous System Progenitor Cells from the Aganglionic Gut of Patients with Hirschsprung's Disease

Enteric nervous system progenitor cells isolated from postnatal human gut and cultured as neurospheres can then be transplanted into aganglionic gut to restore normal patterns of contractility. These progenitor cells may be of future use to treat patients with Hirschprung’s disease, a congenital condition characterized by hindgut dysmotility due to the lack of enteric nervous system ganglia. Here we demonstrate that progenitor cells can also be isolated from aganglionic gut removed during corrective surgery for Hirschsprung’s disease. Although the enteric nervous system marker calretinin is not expressed in the aganglionic gut region, de novo expression is initiated in cultured neurosphere cells isolated from aganglionic Hirschsprung bowel. Furthermore, expression of the neural markers NOS, VIP and GFAP also increased during culture of aganglionic gut neurospheres which we show can be transplantation into cultured embryonic mouse gut explants to restore a normal frequency of contractility. To determine the origin of the progenitor cells in aganglionic region, we used fluorescence-activated cell sorting to demonstrate that only p75-positive neural crest-derived cells present in the thickened nerve trunks characteristic of the aganglionic region of Hirschsprung gut gave rise to neurons in culture. The derivation of enteric nervous system progenitors in the aganglionic gut region of Hirschprung’s patients not only means that this tissue is a potential source of cells for future autologous transplantation, but it also raises the possibility of inducing the differentiation of these endogenous cells in situ to compensate for the aganglionosis.

Laboratory procedures update on Hirschsprung disease

OBJECTIVES

The detection of ganglion cells in rectal biopsies of infants or toddlers with severe constipation is routinely performed by pediatric pathologists in many institutions. Hirschsprung disease (HD) is defined by the lack of ganglion cells (aganglionosis). The early recognition and the prompt implementation of surgical procedures obviously protect infants affected with HD from potential life-threatening conditions, including enterocolitis and debilitating constipation. Image-based and non-image-based clinical techniques and some laboratory tests have been reevaluated along the years, but often fragmentarily. Immunohistochemical markers have been increasingly used in pathology laboratories to detect ganglion cells and nerve fibers. Recently, calretinin, a vitamin D-dependent calcium-binding protein with expression in ganglion cells and nerves, has been described as an adjunctive or primary diagnostic test in HD. The aim of the present study was to systematically summarize and update laboratory procedures targeting ganglion cells in rectal biopsies.

METHODS

Procedures and tests have been reviewed and values of specificity and sensitivity have been calculated according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Contrast enema has the lowest sensitivity and specificity of all of the 3-index investigations under the lens: contrast enema, anorectal manometry, and biopsy with histology. The latter procedure seems to have the highest sensitivity and specificity. Acetylcholinesterase staining on fresh-frozen material has been found to have slightly higher rates of sensitivity and specificity when compared with hematoxylin and eosin only. Calretinin staining may be supportive for the diagnosis, although some cases with false-positivity may be of some concern.

CONCLUSIONS

Hematoxylin and eosin with or without acetylcholinesterase remains the criterion standard according to our PRISMA-based data. In our opinion, the number of false-positive results with potential overtreatment may limit the increasing advocacy for calretinin staining. Both the "primum non nocere" dictum and the "loss aversion heuristic" need to be satisfied harmoniously by preventing harm from unnecessary surgery.

Reevaluation of acetylcholinesterase staining for the diagnosis of Hirschsprung disease and allied disorders

OBJECTIVES

Acetylcholinesterase (AChE) staining has become the gold standard for definitively diagnosing Hirschsprung disease (HD), although some pitfalls have been reported. We reevaluated a large series at our institute in order to validate the accuracy of AChE staining for detecting HD.

METHODS

A retrospective study of the rectal mucosal specimens of all of the children with suspected HD during a 13-year period was performed. The specimens were stained according to the modified Karnovsky-Roots method for AChE staining. The final diagnosis, prognosis, and management after the histopathological diagnosis were analyzed with a questionnaire sent to the patient's original hospital.

RESULTS

Three hundred and fifty-eight specimens were collected. One hundred twenty-two (34%) specimens were diagnosed as HD, 198 (55%) as nonHD, 25 (7%) as "undetermined," and 13 (4%) as "inappropriate." The non-HD group contained 190 (96%) specimens with a normal appearance and 8 (4%) specimens with suspected intestinal neuronal dysplasia (IND). Three hundred and six of 358 questionnaires were returned. The final diagnosis showed that no specimens first diagnosed as HD were identified as non-HD and vice versa, for a sensitivity and specificity of 100%. Four cases were finally diagnosed as chronic idiopathic intestinal pseudo-obstruction (CIIP) in the non-HD group. All of the patients with HD underwent radical surgery. Most non-HD patients were managed conservatively, although some continued to have constipation.

CONCLUSIONS

AChE staining is an accurate tool for differentiating between HD and non-HD with high sensitivity and specificity. CIIP can be included in cases of non-HD; therefore, careful follow-up is mandatory.

Diagnostic accuracy of radiologic scoring system for evaluation of suspicious hirschsprung disease in children

BACKGROUND

In 1996, Donovan and colleagues represented a scoring system for better prediction of Hirschsprung disease (HD).

OBJECTIVES

Our objective was to devise another scoring system that uses a checklist of radiologic and clinical signs to determine the probability of HD in suspicious patients.

PATIENTS AND METHODS

In a diagnostic accuracy study, 55 children with clinical manifestations of HD that referred to a training hospital from 1998 to 2011 were assessed. A checklist was used to evaluate the items proposed by contrast enema (CE), based on six subscales, including transitional zone, rectosigmoid index (RSI), irregular contractions in aganglionic region, cobblestone appearance, filling defect due to fecaloid materials and lack of meconium defecation during the first 48 hours after birth. The patients were classified as high score and low score. Sensitivity, specificity, positive predictive value and negative predictive value of our scoring system were calculated for identifying HD, in comparison with pathologically proved or ruled out HD.

RESULTS

Of the 55 patients, 36 (65.4%) cases had HD and 19 (34.6%) cases were without HD. In the HD group, 32 patients showed high scores and four patients had low scores. The sensitivity and specificity of our diagnostic scoring system were 88.9% (95% CI: 78.6% - 99.1%) and 84.2% (95% CI: 68.7% - 100%), respectively. Moreover, positive predictive value (PPV) and negative predictive value (NPV) were 91.4% (95% CI: 82.1% - 100%) and 80% (95% CI: 62.5% - 97.5%), respectively.

CONCLUSIONS

Our new scoring system of CE is a useful diagnostic method in HD. If a patient's score is high, that patient is highly suspicious to HD and reversely, when one's score is low, the patient presents a reduced probability to be diagnosed with HD.