Aim of the study: Anal canal duplications (ACDs) are extremely rare with only approximately 90 cases described in the literature. We report on three additional patients.
Methods: Cases were analyzed to evaluate presenting symptoms, physical exam and MRI findings. A comprehensive literature review was performed to compare our patients to previously described cases. IRB approval was obtained for this study (19-0394).
Main results: The first female patient presented with an asymptomatic ACD at 2 years old. The second patient was a 13-year-old female with perianal drainage that was initially mistaken for a fistula-in-ano and ultimately found to have an ACD associated with a dermoid cyst. Both posterior midline duplications shared a common wall with the rectum, but did not communicate with it. The ACDs and dermoid cyst were successfully excised through a posterior sagittal approach with no postoperative complications. Histology demonstrated the presence of both squamous epithelium and transitional anal epithelium in each case. The third patient was 8 months old and had a tethered cord, hemisacrum, presacral mass, and anal duplication that was initially undiagnosed. These results corroborate patterns identified in other reports of ACDs with over 90% being female and in the posterior midline. The majority are asymptomatic, but may present with symptoms of local or even systemic infection.
Conclusion: An opening in the midline posterior to the anus should raise clinical suspicion for anal canal duplication. An associated presacral mass must be ruled out. Complete excision through a posterior sagittal approach is recommended upon diagnosis to avoid symptomatic presentations. The key part of the operation is the separation of the ACD from the posterior rectal wall.
Keywords: Anal duplication; Hemisacrum; Presacral mass.