A variant pattern of calretinin immunohistochemistry on rectal suction-biopsies is fully specific of short-segment Hirschsprung's disease.

Abstract

Calretinin immunohistochemistry is now widely used to diagnose Hirschsprung's disease (HD), since loss of calretinin expression within the mucosa and muscularis mucosae of rectal suction-biopsy is pathognomonic of HD. However, a stippled staining may be observed within hypertrophic nerves in the submucosae in some HD patients. The aim of the study was to test the hypothesis that such findings may announce the beginning of the transitional zone. We retrieved 44 consecutive patients (10 girls and 34 boys; median age 6.5 days), diagnosed with aganglionosis on rectal suction biopsies, followed by surgery. According to calretinin immunohistochemistry performed on all paraffin-embedded rectal biopsies, we defined two HD groups: P- showing an absence of any staining within mucosa, muscularis mucosae and submucosa et P+ showing an absence of staining within the mucosa and muscularis mucosae, but a positivity of some submucosal hypertrophic nerves. These data were correlated to the length of total pathological segment (aganglionic and transitional zones) obtained from the original surgery reports. 18/44 patients (40.9 %) belonged to the P+ group and 26/44 (59 %) patients were within the P- group. In the P+ group, the maximal length of the aganglionic zone was 9 cm [mean 4 (1-9)] and the total pathological zone never exceeded 14 cm [mean 8 (3.8-14)]. In the P- group, the maximal length of aganglionic zone was 55.5 cm [mean 11.3 (2.5; 55.5)] and the total pathological zone extended to 59.5 cm [mean 17.75 (4.5; 59.5)]. Aganglionic segment was significantly shorter in the P+ group (p < 0.0001). Staining of some hypertrophic nerves in the submucosa in suction rectal biopsy of HD patients using calretinin immunohistochemistry is only encountered in short-segment aganglionosis with a pathological zone always restricted to rectal and sigmoid colon. This information could be crucial for the surgeons in the decision to choose a transanal procedure.