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Pyloric stenosis: new histopathologic perspective using confocal laser scanning
H Kobayashi1, K Miyahara, A Yamataka
1Department of Pediatric Surgery and the Central Laboratory, Juntendo University School of Medicine, Tokyo, Japan.
Insights
Idiopathic hypertrophic pyloric stenosis (IHPS) in infants is linked to abnormal, thick nerve bundles in the pylorus. Confocal microscopy revealed these contorted nerve structures, offering new insights into IHPS etiology.
Area of Science:
- Gastroenterology
- Pediatric Surgery
- Nerve Biology
Background:
- Idiopathic hypertrophic pyloric stenosis (IHPS) is a common infantile disorder causing gastric outlet obstruction.
- The exact cause of IHPS remains unclear, with recent focus on nerve distribution anomalies.
Purpose of the Study:
- To investigate nerve distribution in the pylorus of infants with IHPS using 3D confocal laser scanning microscopy.
- To compare nerve morphology in IHPS patients with healthy controls.
Main Methods:
- Pylorus biopsy specimens from 6 IHPS infants and 6 controls were analyzed.
- Confocal microscopy with PGP9.5 antibody identified enteric nerve fibers.
- Double immunofluorescence with alpha smooth muscle actin (SMA) marked smooth muscle cells.
Main Results:
- Control pylorus showed thin, interconnected PGP9.5-positive nerve fibers forming a 3D mesh.
- IHPS patient muscle cells were enlarged and round; nerve fibers were thick, contorted, and lacked communication.
- Control muscle cells were thin.
Conclusions:
- Abnormally thick, contorted nerve bundles were identified in the pyloric muscle of IHPS infants.
- These findings were not visible with 2D microscopy.
- The abnormal nerve fibers are suspected to be related to the etiology of IHPS.
Background/Purpose:
Idiopathic hypertrophic pyloric stenosis (IHPS) is a common infantile disorder characterized by enlargement of the pylorus and gastric outlet obstruction. Its complete etiology is still not fully understood, but recent research has focussed on abnormalities of nerve distribution. The authors used confocal laser scanning microscopy to perform 3-dimensional studies of pylorus biopsy specimens taken from cases of IHPS and present their findings.
Methods:
Pylorus biopsy specimens obtained at pyloromyotomy from 6 infants with IHPS were studied using confocal microscopy and compared with 6 control pylorus biopsy specimens from patients without gastrointestinal disease. Biopsy specimens were pretreated to enhance nerve expression by using protein gene product 9.5 (PGP9.5) polyclonal antibody to identify enteric nerve system fibers. Double staining immunofluorescence was used to detect alpha smooth muscle actin (SMA), a smooth muscle marker.
Results:
Control pylorus biopsy specimens showed many thin PGP9.5-positive nerve fibers in the circular and longitudinal muscle layers that communicated with each other to create a 3-dimensional meshlike network. Muscle cells stained by alpha SMA antibody were thin. In contrast, muscle cells from IHPS patients were fat and round. The PGP9.5 staining nerve fibers from IHPS patients formed numerous, thick, and contorted bundles that did not communicate.
Conclusions:
By using confocal laser microscopy the authors were able to identify abnormally thick contorted nerve bundles in the pyloric muscle layers of infants with IHPS. These anormal nerve bundles have not been described previously because of the limitations of 2-dimensional microscopy. The authors suspect that the etiology of IHPS may be related to these abnormal fibers.