Additional criteria in diagnosis of transitional zone in Hirschsprung disease

Abstract

In Hirschsprung disease (HD) transitional zone (TZ) is interposed between aganglionic and normoganglionic zone (NZ). Its presence on proximal resection margin could be reason for postoperative complications in HD patients. A glial cell index (GCI) is the ratio between number of glial cells and ganglion cells in enteric ganglia. The value of GCI in TZ and NZ in HD has not been evaluated previously. The aim of this study was to evaluate GCI and calretinin expression as possible additional tool in differentiation of NZ and TZ in HD. Hematoxylin-eosin and immunohistochemical (calretinin and S-100) staining were performed. NZ and TZ of HD specimens and autopsy rectal specimens were analyzed at 5 microscopic fields (magnification 400×). GCI was analyzed in both myenteric and submucosal ganglia. Myenteric GCI was significantly higher in NZ (7.0±0.64) than in TZ (4.5±1.28), irrelevant of the staining method. Mean value of myenteric GCI less than 6.0 favors TZ origin of sample. Pattern of calretinin expression was different in NZ and TZ. Calretinin positive intrinsic nerve fibers were always present in NZ, mostly in diffuse pattern, while in TZ their presence was variable and often focal. Calretinin expression in myenteric ganglion cells was lower than in submucosal ganglia, especially in TZ. According to our results, myenteric GCI and pattern of calretinin expression could be helpful additional tool in diagnosis of TZ in HD in biopsies with lack of conventional features.