ORIGINAL ARTICLE Histology with immunohistochemistry of the fistula region in female anorectal malformation: Can it be used for neo-anus reconstruction? Anand Pandey , 1 Pinky Pandey, 2 Shailendra P Singh, 1 Savita Agarwal, 2 Vipin Gupta 1 and Rajesh Verma 1 Departments of 1 Surgery, and 2 Pathology, Uttar Pradesh University of Medical Sciences, Saifai, Uttar Pradesh, India Aim: Female anorectal malformation is characterised by communication to the exterior by a fistula. There are conflicting reports of the presence of normal anus in the fistula region. This study was undertaken to assess the histopathology and immunohistochemical correlation of the termi- nal portion of the fistula in female patients and suitability of fistula incorporation in the reconstruction of the neo-anus. Methods: This prospective study included 13 patients of female anorectal malformation. Of these, seven had a vestibular fistula (VF), and the rest had an anterior ectopic anus (AEA). Histopathology of the fistula region was undertaken, along with immunohistochemistry. Various findings were evaluated. Results: Of seven VF patients, four showed atrophic or disrupted internal sphincter smooth muscle, whereas the remaining three showed hyper- tropic internal sphincteric smooth muscle. Six patients showed hypertrophic nerve bundle. Five VF patients showed subepithelial fibrosis, and none of them showed ganglion cells. Of six patients of AEA, internal sphincteric smooth muscle was normal in five. It was hypertrophic in one patient. Transitional epithelium was present in four patients. All patients showed hypertrophic nerve bundle and aganglionosis. Subepithelial fibro- sis was observed in six patients. Conclusion: The fistula region in VF and AEA patients appears to be an abnormal structure. Rather than preservation of the terminal fistulous region, resection followed by anoplasty may be a viable option. Key words: anterior ectopic anus; female anorectal malformation; histology of vestibular fistula; vestibular fistula. What is already known on this topic 1 Anorectal malformation is a common congenital malformation. 2 There is a difference of opinion on the use of the fistula region for neo-anus reconstruction. What this paper adds 1 Histology of the fistula region does not show it to be a nor- mal part. 2 Immunohistochemistry further provides evidence that the fistula region is devoid of the ganglion cells; it had hypertrophic nerve bundles, and there is presence of subepithelial fibrosis. Anorectal malformation (ARM) is an important congenital defect. It presents with a wide spectrum of defects, ranging from rela- tively low malformations to very complex cloacal anomalies. 1 Female ARM is characterised by absent anal opening, and the bowel may be communicating to the exterior by a fistula 2 ; how- ever, other presentations of female ARM do exist. Some investigators have suggested the abnormality of the innervation of this fistula region. 3 Contrary to this, some researchers have found manometric and histological evidence of features of a normal anus in this region, such as the presence of an internal sphincter, transitional epithelium and anal glands and crypts. 4,5 One recent study has refuted this claim. 6 Hence, the use of fistulas for the creation of neo-anus is controversial. This study was undertaken to assess the histopathology and immunohistochemical evaluation of the terminal portion of the fistula in female patients and the suitability of fistula incorpora- tion in the construction of neo-anus in the patients. Methods This study was conducted in the Institute’s hospital from February 2013 to February 2015. It was approved by the hospital research and ethical committee (no. 7914/RIMS&R/Estt-F/2013- 14). All female ARM patients with either vestibular fistula (VF) or anterior ectopic anus (AEA) were included in the study. As per the recent Krickenbeck classification for ARM, 7 VF com- prises either an anus or rectum opening into the vestibule, and the normal anal opening is absent. Thus, the vestibule has three opening – urethra, vagina and fistula. AEA is a regional variant Correspondence: Dr Anand Pandey, Department of Pediatric Surgery, King George’s Medical University, Chowk, Lucknow 226003, India; email: anandpandey@kgmcindia.edu Conflict of interest: None declared. Accepted for publication 21 July 2017. doi:10.1111/jpc.13691 Journal of Paediatrics and Child Health (2017) © 2017 Paediatrics and Child Health Division (The Royal Australasian College of Physicians) 1