Pyloric stenosis: new histopathologic perspective using confocal laser scanning.

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.