A study of calretinin in Hirschsprung pathology, particularly in total colonic aganglionosis

The Diagnostic Value of Immunohistochemistry Markers in Hirschsprung Disease; A Systematic Review and Meta-analysis

BACKGROUND

Immunohistochemistry (IHC) markers are employed to improve the diagnostic yield when testing for Hirschsprung disease (HSCR). Yet, a superior test has not been identified.

OBJECTIVES

We aimed to determine the diagnostic test accuracy (DTA) of IHC markers.

METHODS

We conducted database search for studies reporting IHC staining on rectal biopsy investigating for HSCR. We constructed 2 × 2 contingency tables, and calculated DTA estimates in pooled and paired testing using random-effect model meta-analysis.

RESULTS

Twenty eight IHC markers from 107 studies were used to investigate for HSCR in 10891 children. In pooled analysis; calretinin sensitivity and specificity were superior to acetylcholinesterase, S100, and peripherin [98 % (CI; 0.95-0.99) & 99 % (CI; 0.97-0.99)], [94 % (CI; 0.86-0.97) & 99 % (CI; 0.96-0.99)], [92 % (CI; 0.85-0.96) & 97 % (CI; 0.89-0.99)] and [91.7 % (CI; 0.54-0.98) & 94.8 % (CI; 0.59-0.99)], respectively. In paired analysis calretinin diagnostic odds ratio was superior to hematoxylin and eosin (H&E), acetylcholinesterase and S100: [3349 (PI; 551.3-22667.2) vs 345.3 (PI; 54.9-2394.2)], [300.9 (PI; 13.3-4146.9) vs 34.6 (PI; 2.2-363.9)] and [696.9 (PI; 91.2-3401.7) vs 196.9 (PI; 29.8-890.5)], respectively. In biopsies labelled inadequate for H&E testing, calretinin specificity to rule out HSCR reached 92 % (CI; 0.288-0.998).

CONCLUSIONS

IHC provides additional diagnostic value over H&E. Calretinin appears to be, currently, a superior IHC marker. The available literature is of variable quality, cautious interpretation of the findings should be considered.

LEVEL OF EVIDENCE

III.

Characterization of the Transition Zone in Short Segment Hirschsprung Disease Using Calretinin Immunostaining

Introduction: The detailed expression pattern of calretinin immunohistochemistry in the transition zone (TZ) of Hirschsprung disease (HSCR) has not yet been reported. This study aims to examine the value of calretinin immunohistochemistry for more accurately determining the distal and proximal border of the TZ in short segment HSCR. Methods: Specimens of pull-through surgery from 51 patients with short form of HSCR were analyzed on two longitudinal strips using hematoxylin and eosin (H&E) staining and calretinin immunohistochemistry. Results: In all but two patients, the first appearance of calretinin expression was seen on mucosal nerve fibers before the appearance of any ganglion cells, indicating the distal border of the TZ. The maximum distance between the distal border of the TZ and the proximal border of the TZ, defined by ganglion cells in a normal density on H&E stained sections, a strong calretinin expression on mucosal nerve fibers and in >80% of submucosal and myenteric ganglion cells, with no nerve hypertrophy and absence of ganglionitis was 60 mm. Conclusion: The distal border of the TZ is characterized by calretinin positive intramucosal neurites in nearly all of short form of HSCR and not by calretinin expression on ganglion cells.

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.

Acetylcholinesterase staining for the pathological diagnosis of Hirschsprung's disease

Hirschsprung's disease (HD) is a congenital disease manifesting various degrees of functional bowel obstruction caused by the absence of enteric ganglion cells, which are usually absent in the colonic segment of the HD patient. Because the aganglionic segment of HD always includes the rectum, pathological diagnosis can be made using a rectal sample. HD should be diagnosed as early as possible because serious complications, such as acute enterocolitis or toxic megacolon, can develop without a definitive diagnosis and appropriate treatment. In the mid-1900s, HD was diagnosed by HE staining of specimens obtained by full-thickness biopsy. Since then, the combination of rectal mucosal biopsy and rubeanic acid-amplificated AChE staining has been brought about by the following milestones: the discovery that the submucosal plexus and the intermuscular plexus had the same level of nerve migration; the findings of research on acetylcholine (ACh) and acetylcholinesterase (AChE) in the intestinal tract; and the establishment of a rubeanic acid amplification method. Consequently, the diagnostic rate of HD improved dramatically in the 1980s. This review outlines the history of diagnostic methods for HD, the roles of ACh and AChE in the intestine, and the method of AChE staining.

Identifying Information Needs for Hirschsprung Disease Through Caregiver Involvement via Social Media: A Prioritization Study and Literature Review

Background

Patient and public involvement in health research is important to produce relevant and impactful results.

Objective

This paper aimed to prioritize and summarize Hirschsprung disease (HD)–related information needs among caregivers of children with HD and pediatric surgeons through partnership with a parent-initiated social media campaign.

Methods

We conducted a Web-based survey with the 2 stakeholder groups to identify information needs. The caregiver survey was conducted through a global Web-based community, and the surgeon survey was distributed to members of the Canadian Association of Paediatric Surgeons (CAPS). We conducted a literature review to identify evidence on the prioritized topics.

Results

Our findings showed that 54.9% (89/162) of the individuals completed the caregiver survey and 23.8% (52/218 listed members) of the pediatric surgeons completed the survey distributed through CAPS. Only 20% (18/89) of the caregivers reported being very satisfied or satisfied with the current HD-related resources. A final prioritized list of information needs included bowel management, nutrition and growth, infection, perianal irritation, gastrointestinal pain, surgical diagnostics, and surgical complications. In total, 87 studies were included in the literature review, which included the following: 8 reviews, 2 randomized controlled trials, 74 cohort studies, and 3 practice guidelines. Two priority issues identified by caregivers had only a single study that met the inclusion criteria, whereas 1 topic had none.

Conclusions

With caregiver and surgeon input, we identified 7 information priority areas related to HD. A review of the literature on the priorities found little evidence to support the development of high-quality guidelines. More research is necessary to meet the information needs related to HD as identified by stakeholders.

Development of Nerve Fibre Diameter in Young Infants With Hirschsprung Disease

OBJECTIVES

Finding thickened nerve fibres is one of the key elements in the diagnosis of Hirschsprung disease (HD); however, its value at different ages remains uncertain. Nerve fibre diameters <40 μm can be observed in infants younger than 8 weeks, despite the presence of HD. The aim of this study was to identify a change in maximum nerve fibre diameter in HD patients, measured before and after 8 weeks of age.

METHODS

Nerve fibre diameter was retrospectively evaluated in tissue of 20 infants treated for definite HD. Rectal suction biopsies (RSBs) obtained within the first 8 weeks of life (T1) and resected bowel obtained during primary surgery at an average of 24.7 weeks (T2), were assessed. The 2 thickest nerve fibre diameter recordings at T1 and T2 were compared in each subject, to examine changes in nerve trunk diameter with increasing age.

RESULTS

In 13 cases (65%), nerve fibre diameters were ≥40 μm at T1 and T2. Six subjects (30%) had nerve trunk diameters <40 μm at T1; however, they experienced diameter increases to ≥40 μm by T2. Thus, at T2, 19 subjects (95%) had diameter recordings ≥40 μm. Nerve fibre diameter in the remaining case (5%) stayed consistent at <40 μm at T1 and T2, despite the presence of HD.

CONCLUSIONS

After the first 8 weeks of life, nerve fibre measurements appear to be associated with HD. Measuring the 2 thickest nerve fibres can support typical HD diagnosis criteria beyond 8 weeks of age, but is not superior to histopathological confirmation of aganglionosis.

Diagnostic value of rectal suction biopsies using calretinin immunohistochemical staining in Hirschsprung's disease

BACKGROUND

The study investigates the diagnostic value of calretinin immunohistochemical staining (CIS) on rectal suction biopsies (RSB) in Hirschsprung's disease (HD).

METHODS

A prospective study was conducted at Children's Hospital 2 in Ho Chi Minh City, Vietnam, from January through December 2015. Patients suspected of HD during this period underwent RSB and were followed in order to assess the accuracy of the diagnostic test with CIS compared with conventional histology (H&E).

RESULTS

A total of 188 children with RSB were investigated. Median age was 7.1 (range 0.2-159) months with 65.4% boys. HD was confirmed in 80 (42.6%) children. There were 1 false positive and no false-negative cases. The sensitivity and specificity were 100% (80/80) and 99.1% (107/108) for CIS and 100% and 85.2% for H&E, respectively. Cohen's kappa coefficient was 0.9891 with a diagnostic accuracy of 99.5% for CIS, compared with 0.8303 and 91.5% for H&E, respectively. There were no serious complications related to the RSB.

CONCLUSION

RSB with CIS is a useful diagnostic method for HD, with easy interpretation and no need for cryostat. CIS has a high diagnostic accuracy and should be considered as the primary method for the diagnosis of HD by RSB.

LEVEL OF EVIDENCE

Diagnostic Studies - Level I.

The zebrafish mutant lessen: an experimental model for congenital enteric neuropathies

BACKGROUND

Congenital enteric neuropathies of the distal intestine (CEN) are characterized by the partial or complete absence of enteric neurons. Over the last decade, zebrafish has emerged as a leading model organism in experimental research. Our aim was to demonstrate that the mutant zebrafish, lessen, expressing CEN characteristics, is an equally valuable animal model alongside mammalian models for CEN, by studying its enteric phenotype.

METHODS

The effect of the lessen mutation on the development of the enteric nervous system (ENS), interstitial cells of Cajal (ICC), and intestinal motility in each intestinal region of mutant and wild-type (wt) zebrafish embryos at 3-6 dpf, was analyzed by immunofluorescent detection of neurochemical markers and motility assays.

KEY RESULTS

Development of intestinal motility in the mutant was delayed and the majority of the observed contractions were disturbed. A significant disturbance in ENS development resulted in a distal intestine that was almost free of neuronal elements, in reduced neuronal density in the proximal and mid-intestine, and in a defect in the expression of neurochemical markers. Furthermore, markedly disturbed development of ICC gave rise to a less dense network of ICC.

CONCLUSIONS & INFERENCES

The observed alterations in intestinal motility, intrinsic innervation and ICC network of the mutant in comparison with the wt zebrafish, are similar to those seen in the oligo- and aganglionic regions of the intestine of CEN patients. It is concluded that the zebrafish mutant lessen is an appropriate animal model to investigate CEN.

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.

Gut Feelings About α-Synuclein in Gastrointestinal Biopsies: Biomarker in the Making?

In recent years, several studies have investigated the potential of immunohistochemical detection of α-synuclein in the gastrointestinal tract to diagnose Parkinson's disease (PD). Although methodological heterogeneity has hindered comparability between studies, it has become increasingly apparent that the high sensitivity and specificity reported in preliminary studies has not been sustained in subsequent large-scale studies. What constitutes pathological α-synuclein in the alimentary canal that could distinguish between PD patients and controls and how this can be reliably detected represent key outstanding questions in the field. In this review, we will comment on and compare the variable technical aspects from previous studies, and by highlighting some advantages and shortcomings we hope to delineate a standardized approach to facilitate the consensus criteria urgently needed in the field. Furthermore, we will describe alternative detection techniques to conventional immunohistochemistry that have recently emerged and may facilitate ease of interpretation and reliability of gastrointestinal α-synuclein detection. Such techniques have the potential to detect the presence of pathological α-synuclein and include the paraffin-embedded tissue blot, the proximity ligation assay, the protein misfolding cyclic amplification technique, and the real-time quaking-induced conversion assay. Finally, we will review 2 nonsynonymous theories that have driven enteric α-synuclein research, namely, (1) that α-synuclein propagates in a prion-like fashion from the peripheral nervous system to the brain via vagal connections and (2) that gastrointestinal α-synuclein deposition may be used as a clinically useful biomarker in PD.

Comparative Microarray Analysis of Proliferating and Differentiating Murine ENS Progenitor Cells

Postnatal neural progenitor cells of the enteric nervous system are a potential source for future cell replacement therapies of developmental dysplasia like Hirschsprung's disease. However, little is known about the molecular mechanisms driving the homeostasis and differentiation of this cell pool. In this work, we conducted Affymetrix GeneChip experiments to identify differences in gene regulation between proliferation and early differentiation of enteric neural progenitors from neonatal mice. We detected a total of 1333 regulated genes that were linked to different groups of cellular mechanisms involved in cell cycle, apoptosis, neural proliferation, and differentiation. As expected, we found an augmented inhibition in the gene expression of cell cycle progression as well as an enhanced mRNA expression of neuronal and glial differentiation markers. We further found a marked inactivation of the canonical Wnt pathway after the induction of cellular differentiation. Taken together, these data demonstrate the various molecular mechanisms taking place during the proliferation and early differentiation of enteric neural progenitor cells.

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.

Evaluation of Calretinin as a New Marker in the Diagnosis of Hirschsprung Disease

Background:

Hirschsprung’s disease (HD) is a congenital intestinal motility disorder with absence of ganglion cells in the colonic wall. Diagnosis of the disease is mainly based on the identification of the lack of ganglion cells in the pathology sections of the colon which is very difficult and time consuming and also needs several serial cut sections. There are many proposed markers in this field in the literature but none of them has been satisfactory. Calretinin immunohistochemistry (IHC) has been introduced as a new diagnostic marker to overcome the problems in diagnosis of this disease about 5 years ago. However there are few studies regarding the benefits and pitfalls of this marker.

Objectives:

The aim of this study is to determine the diagnostic value of calretinin IHC in detecting aganglionosis (HD).

Patients and Methods:

27 HD patients and 28 non-Hirschsprung’s disease (NHD) patients were collected in a prospective study and calretinin IHC was performed on 31 aganglionic and 51 normoganglionic full wall thickness sections of colectomies (some of the cases had more than 1 section). The IHC slides were evaluated by two pathologists and the diagnostic value was calculated in comparison with gold standard which is the presence or absence of ganglion cells in serial Hematoxylin and Eosin (HE) stained sections of the colectomies.

Results:

There was great concordance between the final diagnosis of both pathologists and gold standard (k > 0.9). Calretinin immunostaining showed 100% specificity and positive predictive value and more than 90% sensitivity and negative predictive value. High agreement was present between the two pathologists (k > 0.9).

Conclusions:

Calretinin IHC is a very convenient, useful and valuable method to demonstrate aganglionosis in HD patients. Loss of calretinin immunostaining in lamina propria and submucosa is characteristic of HD.

Immunohistochemical panel for the diagnosis of Hirschsprung's disease using antibodies to MAP2, calretinin, GLUT1 and S100

AIMS

The diagnosis of Hirschsprung's disease is currently based on the identification of aganglionosis and the presence of an increase in acetylcholinesterase-positive hypertrophic nerve fibres in the large bowel submucosa. However, acetylcholinesterase staining is laborious and requires a skilled technician. The aim of this study was to identify a method for diagnosing Hirschsprung's disease reliably using an immunohistochemical panel of recently proposed markers.

METHODS AND RESULTS

Sixty-nine specimens from 37 patients were evaluated. MAP2 and calretinin antibodies were shown to stain ganglia reliably in the submucosal and myenteric plexuses of normal tissue. By contrast, reduced staining of ganglia was observed in patients with Hirschsprung's disease. Staining for GLUT1 and S100 was used to evaluate the number and thickness of nerve fibres. Gain of GLUT1 and S100 expression was in contrast to the loss of calretinin and MAP2. Hypertrophic submucosal nerve fibres in Hirschsprung's disease develop a perineurium with a ring-like GLUT1 staining pattern similar in size and intensity to that observed in deeper subserosal tissue.

CONCLUSIONS

The diagnosis of Hirschsprung's disease using immunohistochemical panels could be as accurate as with conventional frozen section techniques. In particular, the use of a combination of markers for ganglia and hypertrophic nerve fibres highlighting a prominent perineurium in Hirschsprung's disease could be an alternative method.

SRY interference of normal regulation of the RET gene suggests a potential role of the Y-chromosome gene in sexual dimorphism in Hirschsprung disease

The Hirschsprung disease (HSCR) is a complex congenital disorder, arising from abnormalities in enteric nervous system (ENS) development. There is a gender disparity among the patients, with the male to female ratio as high as 5 : 1. Loss-of-function mutations of HSCR genes and haploinsufficiency of their gene products are the primary pathogenic mechanisms for disease development. Recent studies identified over half of the HSCR disease susceptibility genes as targets for the sex-determining factor SRY, suggesting that this Y-encoded transcription factor could be involved in sexual dimorphism in HSCR. Among the SRY targets, the tyrosine kinase receptor RET represents the most important disease gene, whose mutations account for half of the familial and up to one-third of the sporadic forms of HSCR. RET is regulated by a distal and a proximal enhancer at its promoter, in which PAX3 and NKX2-1 are the resident transcription factors respectively. We show that the SRY-box 10 (SOX10) co-activator interacts and forms transcriptional complexes with PAX3 and NKX2-1 in a sequence-independent manner and exacerbates their respective transactivation activities on the RET promoter. SRY competitively displaces SOX10 in such transcription complexes and represses their regulatory functions on RET. Hence SRY could be a Y-located negative modifier of RET expression; and if it is ectopically expressed during ENS development, such SRY repression could result in RET protein haploinsufficiency and promotion of HSCR development, thereby contributing to sexual dimorphism in HSCR.

Predictive value of nerve trunk size in the neonate

PURPOSE

The diagnosis of Hirschsprung's disease (HD) remains challenging. The identification of ganglion cells is difficult and acetycholine esterase (AChE) staining can be subject to a great variability, particularly in the neonatal period (<8 weeks). Nerve trunks greater than 40 µm are considered to be predictive for HD. The aim of this study was to evaluate the usefulness of measuring nerve trunk size in the newborn with HD.

METHODS

Out of 292 biopsies 69 could be reanalyzed by three independent researchers. 40 µm was used as cutoff point for nerve trunk size. They were subdivided into three groups: (a) diagnosis of HD certain at the first biopsy, (b) no HD and (c) diagnosis of HD remains doubtful and re-biopsy taken.

RESULTS

In 87 % of group A nerve trunk size was ≥ 40 µm (SD 13.8). In 84 % of group B trunk size was < 40 µm (SD 16.2). In group C only 60 % of the patients showed a positive correlation between final diagnosis and nerve trunk size.

CONCLUSION

Using 40 µm as the cutoff point gave 13 % false-negative and 16 % false-positive cases. Measurement of the nerve trunk in the neonatal period does not seem to be a reliable method for detecting HD.

Calretinin-immunoreactive mucosal innervation in very short-segment Hirschsprung disease: a potentially misleading observation

Absent calretinin-immunoreactive (CRir) mucosal innervation in aganglionic rectal biopsies is considered a useful diagnostic finding for Hirschsprung disease. Analysis of a series of rectosigmoid resections from patients with short-segment (>2-cm aganglionic, n  =  9) and very short-segment (≤2-cm aganglionic, n  =  9) Hirschsprung disease demonstrates that CRir mucosal nerves extend into the proximal 1-2 cm of aganglionic bowel, where their presence in distal rectal biopsies could complicate diagnosis of very short-segment disease. Indeed, retrospective analysis of preoperative, aganglionic, distal rectal biopsies from 4 of 9 patients with very short-segment Hirschsprung disease revealed CRir mucosal innervation. Accurate diagnosis was possible based on generous histopathological submucosal sampling to exclude ganglion cells and the presence of abundant large-caliber submucosal nerves (more than 4 nerves >30 µm thick/×200 field or more than 2 nerves >40 µm thick/×200 field). Absent CRir mucosal innervation supports the diagnosis of Hirschsprung disease, but the presence of CRir mucosal nerves does not exclude aganglionosis, especially in distal rectal biopsies from patients with very short-segment Hirschsprung disease.

What neurons hide behind calretinin immunoreactivity in the human gut?

Calretinin (CALR) is often used as an immunohistochemical marker for the histopathological diagnosis of human intestinal neuropathies. However, little is known about its distribution pattern with respect to specific human enteric neuron types. Prior studies revealed CALR in both myenteric and submucosal neurons, most of which colabel with choline acetyl transferase (ChAT). Here, we specified the chemical code of CALR-positive neurons in small and large intestinal wholemounts in a series of 28 patients. Besides other markers, we evaluated the labeling pattern of CALR in combination with vasoactive intestinal peptide (VIP). In colonic submucosa, CALR and VIP were almost completely colocalized in about three-quarters of all submucosal neurons. In the small intestinal submucosa, both the colocalization rate of CALR and VIP as well as the proportion of these neurons were lower (about one-third). In the myenteric plexus of both small intestine and colon, CALR amounted to 11 and 10 %, respectively, whereas VIP to 5 and 4 % of the whole neuron population, respectively. Colocalization of both markers was found in only 2 and 3 % of myenteric neurons, respectively. In section specimens, nerve fibers coreactive for CALR and VIP were found in the mucosa but not in the muscle coat. Summarizing the present and earlier results, CALR was found in at least one submucosal and two myenteric neuron populations. Submucosal CALR+/VIP+/ChAT± neurons innervate mucosal structures. Furthermore, CALR immunoreactivity in the myenteric plexus was observed in morphological type II (supposed primary afferent) and spiny type I (supposed inter- or motor-) neurons.

Hirschsprung's disease: the importance of early diagnosis

Congenital intestinal aganglionosis, also called Hirschsprung disease (HD), is defined as the absence of ganglionic cells in the myenteric (Auerbach) and submucosal (Meissner) plexus, due to a failure in the enteric nervous system development. The extent of intestinal involvement may vary according to the age of embryo development in which this failure occurs. It is not unusual for other malformations to be present, as well as chromosomal trisomies, manly trisomy 21. Enterocolitis is a frequent, life threatening, and feared complication of HD. Moreover, oligohydramnios is a well-known condition frequently associated with malformations, including those related to the gastrointestinal tract. The authors report the case of a newborn that presented a delayed meconium passage. On the third day of life, he presented enterocolitis—the outcome of which was favorable with clinical treatment. While the diagnosis of HD was awaiting confirmation, the enterocolitis relapsed and this time he died due to septic shock. The autopsy findings were compatible with a short segment of congenital intestinal aganglionosis. No other malformation was found. The authors call attention for an early diagnosis of HD whenever the meconium passage does not happen for at least 48 hours and for the risk factors of enterocolitis. This case also demonstrates HD associated with oligohydramnios.