Epithelial and ganglionic distribution at the distal rectal end in anorectal malformations: could it play a role in anastomotic adaptation?

Purpose In anorectal malformations (ARMs), the epithelium of the distal rectal end is not well described. We histomorphologically evaluated epithelial and ganglionic distribution in the distal rectal end of ARMs resected during anorectoplasty to assess similarities and differences with normal anal canal structure. Methods In this single-center retrospective study, specimens from 60 ARM patients (27 males, 33 females) treated between 2008 and 2019 were evaluated. Results Epithelium type and alignment sequence as well as ganglionic distribution were similar in the distal rectal end and in a normal anal canal. Stratified columnar epithelium (anal transitional zone, ATZ) was seen in 49/60 (81.7%) cases and in all ARM types, including the no-fistula type. Anal crypts were identified in the stratified columnar epithelium (ATZ) of 46/49 (93.9%) patients. Regarding distal rectal end-resecting anorectoplasty, in 90% of patients, resection was performed distal to the Herrmann line. Ganglion cell distribution was exclusively proximal to the Herrmann line. Conclusion Epithelial and ganglionic distribution was similar in the distal rectal end of ARMs and in a normal anal canal. The ATZ is the epithelial boundary between the rectum and skin in a normal anal canal. ATZ preservation could reproduce anal canal structure in ARM reconstruction.