EP326 - Rectal Duplication Cyst: A Case Report

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Purpose/Background: Gastrointestinal duplications are rare, occurring in 1 in 4500 births. Of these, foregut and midgut duplication cysts are more common, with only about 4% of duplications occurring in the rectum. These are referred to as duplications due to the histopathologic duplication of the gastrointestinal tissue from which they arise. They are often asymptomatic and found incidentally. We present a case of asymptomatic rectal duplication cyst, its diagnostic workup and surgical management.

Methods/Interventions: We present the case of a 30-year-old woman who presented with a cystic presacral mass found incidentally on routine ultrasound for pregnancy monitoring. This was followed throughout her pregnancy and was stable. After delivery, she presented for further evaluation and management of this mass. An MRI was obtained showing a 5.1 x 4.5 x 4.8cm cystic, homogenous mass latero-posterior to the rectum, without concerning aggressive features or nodularity, and inseparable from the left posterior rectal wall. She was presented at tumor board and the mass was thought to be likely benign, so no further workup or biopsy was undertaken. Given the mass was low and presacral, the patient was offered excision of the mass through a posterior perineal approach. In the prone Kraske position, an incision was made posterior to the anus and dissection was carried down to the pelvic floor where the mass was encountered. This was circumferentially dissected off the sacrum posteriorly and off the rectal wall. A sigmoidoscopy with leak test was performed with no leak noted prior to layered closure over a drain.

Results/Outcomes: The patient’s hospital recovery was uncomplicated. The patient’s urinary catheter was removed post-operative day 1 and her diet was advanced to regular. The drain remained serosanguineous and the patient was discharged home on post-operative day 2. She was seen again in clinic one week post-operatively. Pathology returned as benign squamous and ciliated epithelial-lined cyst with hypertrophic smooth muscle cyst wall, likely rectal duplication cyst with metaplastic cyst lining, with no evidence of malignancy. The drain output was mostly unchanged, and the drain was removed in clinic. Overall, the patient’s recovery was uncomplicated and she is healing well.

Conclusion/Discussion: Rectal duplication cysts are rare, and often present as a cystic mass in the presacral space. There are many different surgical approaches to their excision depending on the size and the location of the cyst. We presented a case of posterior perineal approach to the excision of a rectal duplication cyst, along with its inpatient and outpatient post-operative course.