Abnormal choline transporter immunohistochemical staining in older children with chronic constipation not associated with Hirschsprung disease.

Objective: Choline transporter (ChT) immunohistochemistry (IHC) is a new ancillary test that aids in the diagnosis of Hirschsprung disease in newborns and infants. The behavior of this stain in older children (greater than 1 year of age) with chronic constipation, where Hirschsprung disease is clinically unlikely, has not been investigated. The aim of our study was to determine the behavior of ChT IHC in rectal biopsies performed on older children with chronic constipation.

Methods: We performed ChT IHC on 54 endoscopically obtained mucosal biopsies from 41 patients with chronic constipation. For comparison, ChT IHC was also performed on 12 endoscopically obtained mucosal biopsies from 8 nonconstipated children, 11 rectal suction biopsies from 9 infants, and 6 full-thickness biopsies from 5 older children with confirmed Hirschsprung disease. We reviewed the ChT IHC staining and quantified the number of positive staining neurites in the muscularis mucosae.

Results: Of the 54 rectal biopsies from children with chronic constipation, 13 (24%) showed an aganglionic staining pattern, and 7 (13%) showed equivocal staining. The number of immunoreactive neurites in the muscularis mucosae in constipated children without Hirschsprung disease, however, was substantially lower than seen in patients with Hirschsprung disease. In comparison, in children without constipation, most biopsies showed a ganglionic pattern (11/12 [92%]). All biopsies from the Hirschsprung disease group demonstrated an aganglionic pattern.

Conclusions: In our cohort, ChT IHC showed an abnormal/aganglionic or equivocal pattern in 37% of patients with chronic constipation. As such, ChT IHC results should be interpreted with caution when performed on rectal biopsies in chronically constipated children.