Selected topics in the evaluation of pediatric gastrointestinal mucosal biopsies

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.

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.

Gastrointestinal endoscopy and mucosal biopsy in the first year of life: indications and outcome

OBJECTIVES

Lower threshold and widening indications for paediatric gastrointestinal endoscopy have resulted in a significant increase in the numbers of endoscopic procedures performed in infants. Despite this, knowledge of gastrointestinal mucosal findings in this age group is limited and data on the clinical usefulness of endoscopy are lacking.

METHODS

All of the children younger than 1 year referred to a single tertiary paediatric gastroenterology unit during the period June 1987 to August 2007 who underwent gastrointestinal endoscopy were identified and the clinical indications and histological outcomes were reviewed.

RESULTS

A total of 933 gastroesophageal duodenoscopies and 439 colonoscopies were performed in 1024 cases in a total of 823 infants. In order of frequency, clinical indications were diarrhoea (51%), failure to thrive (41.2%), symptoms of reflux (27.1%), and rectal bleeding (8.5%). Mucosal biopsies were insufficient for assessment in only 2.4% of cases. Mucosal histology was normal in 33.8%, whereas histological abnormalities were identified in 63.8%. Specific histological diagnoses included microvillous inclusion disease, autoimmune enteropathy, graft-versus-host disease post-bone marrow transplantation, tufting enteropathy, and disaccharidase deficiency. There was only 1 colonic perforation complicating endoscopy in a total of 889 cases for which relevant information was available (0.1%).

CONCLUSIONS

In two-thirds of cases, histological abnormalities were detected that influenced management following endoscopic examination and mucosal biopsy in infants. Endoscopy with biopsies is a greatly informative test with low failure and complication rates in the first year of life.