Morphometric determination of the methodological criteria for the diagnosis of intestinal neuronal dysplasia (IND B)

Intestinal Neuronal Dysplasia Type B: An Updated Review of a Problematic Diagnosis

Context.—

Intestinal neuronal dysplasia type B (IND B) is a controversial histopathologic phenotype that has been associated with intestinal dysmotility, either as an isolated condition or in conjunction with established pathologic disorders (eg, Hirschsprung disease). Many factors contribute to the debate over the existence and/or clinical significance of IND B, including a large body of published data based on inconsistent diagnostic criteria and methods, which have fostered many unwarranted conclusions that lack sufficient scientific basis.

Objective.—

To critically analyze existing published data regarding IND B to provide supporting evidence-based diagnostic practice and to stimulate necessary and scientifically sound research.

Data Sources.—

This update focuses on published literature related to the pathology of IND B because without a reliable pathologic diagnosis, studies of epidemiology, pathogenesis, natural history, management, and outcome are all suspect. Problems with existing data are identified explicitly with suggestions as to how future investigations should be designed and evaluated to better understand this entity.

Conclusions.—

Inconsistencies in diagnostic criteria and methods used to define IND B justifiably encumber the universal acceptance of IND B as a neuropathologic etiology for intestinal dysmotility. IND B will remain a controversial diagnosis until rigorous, well-controlled scientific studies are conducted to establish reproducible and reliable diagnostic criteria that reliably translate from one laboratory to another.

Intestinal Neuronal Dysplasia-Like Submucosal Ganglion Cell Hyperplasia at the Proximal Margins of Hirschsprung Disease Resections

Intestinal neuronal dysplasia type B (IND) denotes an increased proportion of hyperplastic submucosal ganglia, as resolved histochemically in 15-μm-thick frozen sections. IND has been reported proximal to the aganglionic segment in patients with Hirschsprung disease (HSCR) and is putatively associated with a higher rate of postsurgical dysmotility. We developed and validated histological criteria to diagnose IND-like submucosal ganglion cell hyperplasia (IND-SH) in paraffin sections and used the approach to study the incidence and clinical and/or genetic associations of IND-SH at the proximal margins of HSCR pull-through resection specimens. Full-circumference paraffin sections from the proximal margins of 64 HSCR colonic pull-through specimens and 24 autopsy controls were immunostained for neuron-specific Hu antigen, and nucleated ganglion cells in each submucosal ganglion were counted. In controls, an age-related decline in the relative abundance of "giant" ganglia (≥7 nucleated Hu-positive [Hu+] ganglion cells) was observed. A conservative diagnostic threshold for IND-SH (control mean ± 3× standard deviation) was derived from 15 controls less than 25 weeks of age. No control exceeded this threshold, whereas in the same age range, IND-SH was observed at the proximal margins in 15% (7 of 46) of HSCR resections, up to 15 cm proximal to the aganglionic segment. No significant correlation was observed between IND-SH and length of or distance from the aganglionic segment, sex, trisomy 21, RET or SEMA3C/D polymorphisms, or clinical outcome, but analysis of more patients, with better long-term follow-up will be required to clarify the significance of this histological phenotype.

A practical guide for the diagnosis of primary enteric nervous system disorders

OBJECTIVE

Primary gastrointestinal neuropathies are a heterogeneous group of enteric nervous system (ENS) disorders that continue to cause difficulties in diagnosis and histological interpretation. Recently, an international working group published guidelines for histological techniques and reporting, along with a classification of gastrointestinal neuromuscular pathology. The aim of this article was to review and summarize the key issues for pediatric gastroenterologists on the diagnostic workup of congenital ENS disorders. In addition, we provide further commentary on the continuing controversies in the field.

RESULTS

Although the diagnostic criteria for Hirschsprung disease are well established, those for other forms of dysganglionosis remain ill-defined. Appropriate tissue sampling, handling, and expert interpretation are crucial to maximize diagnostic accuracy and reduce interobserver variability. The absence of validated age-related normal values for neuronal density, along with the lack of correlation between clinical and histological findings, result in significant diagnostic uncertainties while diagnosing quantitative aberrations such as hypoganglionosis or ultrashort Hirschsprung disease. Intestinal neuronal dysplasia remains a histological description of unclear significance.

CONCLUSIONS

The evaluation of cellular quantitative or qualitative abnormalities of the ENS for clinical diagnosis remains complex. Such analysis should be carried out in laboratories that have the necessary expertise and access to their own validated reference values.

Classification and diagnostic criteria of variants of Hirschsprung's disease

"Variants of Hirschsprung's disease" are conditions that clinically resemble Hirschsprung's disease (HD), despite the presence of ganglion cells in rectal suction biopsies. The diagnosis and management of these patients can be challenging. Specific histological, immunohistochemical and electron microscopic investigations are required to characterize this heterogeneous group of functional bowel disorders. Variants of HD include intestinal neuronal dysplasia, intestinal ganglioneuromatosis, isolated hypoganglionosis, immature ganglia, absence of the argyrophil plexus, internal anal sphincter achalasia and congenital smooth muscle cell disorders such as megacystis microcolon intestinal hypoperistalsis syndrome. This review article systematically classifies variants of HD based on current diagnostic criteria with an additional focus on pathogenesis, epidemiology, clinical presentation, management and outcome.

Colonic Pseudo-Obstruction with Distinct Transitional Zone in Adult Constipation Patients: Pathological Analysis and Results of Surgical Treatment

There are subsets of chronic constipation patients showing features of colonic pseudo-obstruction (CPO) with distinct transitional zone (TZ). We intended to analyze the clinicopathologic characteristics and surgical outcomes of these patients. Twenty-five consecutive patients who underwent surgery for constipation over the 9-year period were analyzed. TZ (+) group was defined as patients showing symptoms or signs of large bowel obstruction with dilated proximal and collapsed distal colon around the TZ at the time of operation, but without any evidence of mechanical causes of obstruction. Nineteen (76%) patients had features of CPO with TZ. All TZs were located in the left colon. Pathologically, segmental hypoganglionosis was identified at the TZ in all TZ (+) patients. On the other hand, pathologic diagnosis was intestinal neuronal dysplasia type B in the remaining six (24%) patients having a uniform colon diameter without demonstrable dilatations (TZ (-) group). Among TZ (+) patients, 17 (90%) underwent total colectomy with ileorectal anastomosis and two (10%) underwent enterostomy. Long-term follow-up (median 56 months) showed no recurrence of constipation in this group of patients. All six TZ (-) patients underwent total colectomy with ileorectal anastomosis and two (33%) of them had persistent symptoms of constipation on long-term follow-up (median 60 months). In a subset of adult constipation patients presenting with features of CPO with TZ, segmental hypoganglionosis was the final pathologic diagnosis. Constipation patients with features of CPO with distinct TZ in the left colon are expected to benefit from surgical intervention.

Gastrointestinal neuromuscular pathology in chronic constipation

Some patients with chronic constipation may undergo colectomy yielding tissue appropriate to diagnosis of underlying neuromuscular pathology. The analysis of such tissue has, over the past 40 years, fueled research that has explored the presence of neuropathy, myopathy and more recently changes in interstitial cells of Cajal (ICC). In this chapter, the data from these studies have been critically reviewed in the context of the significant methodological and interpretative issues that beset the field of gastrointestinal neuromuscular pathology. On this basis, reductions in ICC appear to a consistent finding but one whose role as a primary cause of slow-transit constipation requires further evaluation. Findings indicative of significant neuropathy or myopathy are variable and in many studies subject to considerable methodological bias. Methods with practical diagnostic utility in the individual patient have rarely been employed and require further validation in respect of normative data.

What is new in radiology and pathology of motility disorders in children?

Disorders affecting colorectal motility lead to significant morbidity in children with surgical conditions. Etiology is frequently unknown, which in turn makes treatment empiric and compromises outcome. A thorough understanding of the normal mechanisms of control and the ability to recognize and manage defects is an important goal for clinicians. This article reviews recent advances made in the investigation of children with colorectal motility disorders, including the role of transit studies (marker studies and scintigraphy), options for assessing anatomy (ultrasound, contrast enema, and sectional imaging) and the use of manometry, both anorectal and colonic. Current concepts in microscopic evaluation are outlined.

[Intestinal neuronal dysplasia type B: how do we understand it today?]

Intestinal neuronal dysplasia type B (IND B) is currently considered to be a subtle malformation of the submucosal plexus, leading to an increased proportion of over-sized ganglia and potentially accompanied by a mild, chronic gastrointestinal motility disturbance. The diagnosis of IND B is morphologically based and involves the demonstration of an increased proportion of giant ganglia in the submucous plexus related to the patient's age. Giant ganglia are physiologically frequent in the neonatal period. Therefore, IND B should not be diagnosed prior to 1 year of age. Morphological features of IND B may occur as an isolated finding or may be observed proximal to an aganglionic segment. IND B and constipation may resolve spontaneously up to the age of 4 years. Treatment of IND B is usually conservative, surgical resection is currently deemed necessary only in a minority of patients. The pathogenesis of IND B is still incompletely understood and the etiology unknown. Future research on the basis of standardized diagnostic conditions is expected to result in a better understanding of this disease, and to reveal the cause of aberrant ganglion development.

[Intestinal neuronal dysplasia type B: how do we understand it today?]

Intestinal neuronal dysplasia type B (IND B) is currently considered to be a subtle malformation of the submucosal plexus, leading to an increased proportion of over-sized ganglia and potentially accompanied by a mild, chronic gastrointestinal motility disturbance. The diagnosis of IND B is morphologically based and involves the demonstration of an increased proportion of giant ganglia in the submucous plexus related to the patient's age. Giant ganglia are physiologically frequent in the neonatal period. Therefore, IND B should not be diagnosed prior to 1 year of age. Morphological features of IND B may occur as an isolated finding or may be observed proximal to an aganglionic segment. IND B and constipation may resolve spontaneously up to the age of 4 years. Treatment of IND B is usually conservative, surgical resection is currently deemed necessary only in a minority of patients. The pathogenesis of IND B is still incompletely understood and the etiology unknown. Future research on the basis of standardized diagnostic conditions is expected to result in a better understanding of this disease, and to reveal the cause of aberrant ganglion development.

Intestinal neuronal dysplasia type B: one giant ganglion is not good enough

In this "Current Practice in Pediatric Pathology" article, 2 experts in the field and an associate editor of Pediatric and Developmental Pathology discuss the definition, diagnosis, clinical significance, and management of intestinal neuronal dysplasia type B. Intestinal neuronal dysplasia type B has constituted a diagnostic challenge ever since its first description more than 30 years ago. Intestinal neuronal dysplasia type B is regarded by many as a subtle malformation of the enteric nervous system that is limited to the submucosal plexus of the colon. The precise etiology remains unknown, and, to date, no specific diagnostic test exists other than morphology. Over time, with increasing experience, obligate pathological features have been adapted and refined, leading to contemporary diagnostic criteria that are enunciated in this review and placed into context with prior published data. Rigorous application of these criteria, under standardized laboratory conditions, is crucial for accurate diagnosis and future advances in this field.

Paediatric constipation for adult surgeons--article 1: targeting the cause

Constipation is very common in all age groups and can be resistant to standard therapies, producing chronic morbidity. Childhood onset constipation frequently produces symptoms that persist into adulthood. Recent advances have been made in the diagnosis and treatment of childhood constipation that could have application in adult practice. In the first part of the present review, the methods of differentiation of patients with a disorder of colonic motility from those with an anorectal hold-up are discussed. Slow transit constipation, with distinct features on colonic manometry and scintigraphy, has only recently been recognized in children. This diagnosis, together with a novel method of placement of a manometric catheter, is described. While the cause of slow transit constipation remains unclear, clinical features that differ between children and adults may provide an insight into the aetiology. The diagnosis of intestinal neuronal dysplasia is explained and the controversy surrounding the diagnosis outlined. We propose that the traditional histological criteria exclude many other clinically significant forms of dysplasia of the enteric nervous system and should be extended.

Alterations of enteric nerve plexus in experimental gastroschisis: is there a delay in the maturation?

BACKGROUND/PURPOSE

After surgical correction of gastroschisis, intestinal transitory hypoperistalsis usually occurs. Long-term parenteral nutrition often is necessary leading to a higher morbidity associated with this malformation. The etiology of this transitory intestinal hypomotility is unknown. It may be caused by a reversible inflammatory process in the intestinal wall or other causes, including an alteration of the maturation of intestinal neural plexus, because the disturbance disappears spontaneously after a variable period. The aim of this work was to study the neuronal cells of the myenteric plexus of the fetal intestine in experimental gastroschisis. The main hypothesis was that the transitory intestinal dismotility seen in gastroschisis could be secondary to alteration in the maturation of the enteric nervous plexus.

METHODS

Twenty-seven time-mated rabbits, on gestational day 25, were submitted to a midline laparotomy; the gravid bicornuate uterus was exposed and opened, and the more distal fetuses relative to the vaginal opening had the abdominal wall opened by a small incision to produce gastroschisis (n = 29). The fetuses not submitted to gastroschisis were used as controls (n = 12). The amniotic fluid was carefully aspirated from the opened uterus and saved for later repositions. On gestational day 30, the does were again submitted to general anesthesia, and the fetuses were delivered by cesarean section. The fetal intestine was removed, the adjacent mesentery excised, and intestinal specimens were harvested for histologic studies. The specimens were stained for acetyl-cholinesterase activity (AChE) to assess the maturity of the nervous enteric cells and for lactate dehydrogenase (LDH) that identify specifically immature nervous cells. The histologic sections stained by LDH were submitted to histomorphometric analysis of the nervous cells through an image system analysis (Kontron 300). The results were submitted to statistical analyses (P <.05).

RESULTS

Macroscopic alterations of the fetal gastroschisis intestine are similar to the human findings: shortening of the intestine, intestinal wall thickening, and a hypertrophied muscular layer. In the gastroschisis group, histologic AChE activity was decreased in comparison with control intestines. The histomorphometric assessment in slices stained with LDH, which identify immature nervous cells, showed that the neuronal intestinal cells of the gastroschisis group were significantly smaller and more numerous relative to the control group.

CONCLUSIONS

There were significant differences in the nervous plexus of the intestine of fetuses with gastroschisis relative to the controls. The observed morphologic changes may be caused by alteration in the maturation of the intestinal neuronal in gastroschisis. This alteration may explain the transitory intestinal hypomotility observed in infants after surgical correction of gastroschisis.

Neuronal dysplasia: A controversial pathological correlate of intestinal pseudo-obstruction

The infant or child with intestinal pseudo-obstruction poses many challenges for geneticists and other specialists. Although a well-defined anatomic diagnosis (e.g., Hirschsprung disease) can be established for a subset of patients, the pathological correlates for many patients are non-existent or controversial. Intestinal neuronal dysplasia (IND) is frequently considered in the differential diagnosis, despite the fact that existence and significance of the abnormal histopathological features that characterize IND are hotly debated. This review highlights some of the concerns regarding this diagnosis including problems with the diagnostic criteria, the manner in which these criteria are applied in contemporary pathology practices, and the likelihood that many of the pathological findings are secondary consequences of impaired motility with no other clear clinical significance. Possible genetic and developmental bases for IND are also discussed.

Morphometric quantification of normal submucous plexus in the distal rectum of adult healthy volunteers

OBJECTIVE

Inadequate morphometric characterization of the normal adult submucous plexus has precluded the diagnosis of colonic dysganglionoses associated with constipation, such as intestinal neuronal dysplasia type B (IND B). The internal submucous plexus (Meissner plexus) was morphometrically quantified in adult healthy volunteers.

DESIGN

Open, prospective morphometric study in balanced groups of female and male volunteers.

PARTICIPANTS

Thirty-seven adult healthy male and female volunteers with normal bowel function and no history of gastrointestinal disease.

METHODS

Four jumbo rectal biopsies (3-5 mm3) were taken 5 and 10 cm above the pectinate line. Two expert gastrointestinal pathologists assessed biopsy sections after specific nerve cell staining for lactic dehydrogenase, nitric oxide synthase and acetylcholinesterase, mainly for characteristics of ganglia and nerve cells in the submucous plexus.

RESULTS

No healthy individual demonstrated over 20% of submucosal ganglia as giant ganglia or more than four giant ganglia per 30 sections (the morphometric criteria for IND B). Single submucosal nerve cells and ganglion numbers halved between 10 and 5 cm above the pectinate line, but there were no age or gender differences. The biological variability of nerve cell and ganglion density in the submucous plexus was large.

CONCLUSIONS

Healthy adults show less than 20% of submucosal ganglia as giant ganglia and no more than four giant ganglia per 30 rectal biopsy sections. There is therefore no overlap with the histomorphological criteria of IND B. These data therefore support the specificity of the previously defined criteria for IND B in adults.

Rectal mucosal biopsy compared with laparoscopic seromuscular biopsy in the diagnosis of intestinal neuronal dysplasia in children with slow-transit constipation

BACKGROUND/PURPOSE

Intestinal neuronal dysplasia (IND) as a cause for severe chronic constipation remains controversial. The aim of this study is to examine the correlation between a deficiency of substance P (SP) immunoreactive nerve fibers in the colon and enzyme histochemistry of rectal biopsies in children with slow-transit constipation.

METHODS

Fifty children with intractable constipation have been assessed by rectal biopsies examined with histochemical staining for lactate dehydrogenase, and 32 children among those 50 have been studied by laparoscopic seromuscular biopsy of the colon labelled with antibodies to SP using immunofluorescence methods.

RESULTS

Four children have evidence of IND. Fifteen children, including all 4 IND cases, showed a deficiency of SP immunoreactivity. There is a significant correlation between giant ganglia and SP deficiency (P <.01).

CONCLUSION

This study is attempting to propose that a deficiency of SP immunoreactivity in colonic circular muscle nerves may be used as a histologic marker for slow-transit constipation and that IND may be a small subset of patients with SP deficiency.