EP1041 - Abdominoperineal resection and Abdominal Wall Reconstruction for Management of Anal Mucinous Adenocarcinoma in a 27 year old Down Syndrome Patient

Purpose/Background: Signet cell mucinous adenocarcinoma of anal canal is very rare, accounting for 0,1% to 2,4% of all colorectal malignancies, with a dismall prognosis and limited response to chemoradiation therapy, affecting patients in the mid 60 years old. Its main treatment is abdominoperineal resection with end colostomy, with its specific morbidity as paraostomal hernias and difficulties in pouch appliance necessitating additional surgeries.

Methods/Interventions: We describe the case of a 27 years old male patient with Down's Syndrome operated several times in his childhood for Hirschsprung's disease and living for more than 20 years with a cecostomy and a left colon mucos fistula with no pouch appliance and a chronic inflammation in the abdominal wall. Two months prior the first clinical appointment, he presented anal pain, bleeding and mucous discharge; upon physical examination, there was a mass in the anal canal and an extensive inflammation in the left abdominal wall around the cecostomy and the mucous fistula. Biopsy revealed signet cell mucinous adenocarcinoma confirmed by immunohistochemistry. RM imaging described an extensive neoplasia with 8cm in the longitudinal axis in the anal canal extending upwards and with apparent invasion of the intersphincteric space. After a MDT discussion, we proceeded to an abdominoperineal resection with resection of the cecostomy and the left colon remnant, construction of an ileostomy in the right abdominal wall and reconstruction of the left abdominal wall defect with negative pressure wound therapy device.

Results/Outcomes: Postoperatively, the patient presented with surgical site infection and was submitted to two additional surgeries for change of the vacuum device and resuturing of the abdominal wall; the postoperative course after these surgeries was uneventful and the patient was discharged at the 17 postoperative day with a small open area in the surgical incision granulating by secondary intention. Final pathology revealed a pT3pN0 (20 nodes) signet cell mucinous adenocarcinoma of the anal canal with 6,5cm longitudinal extension, angiolymphatic and perineural invasion and compromised circunferencial resection margin (R1 resection). The patient is now being evaluated for adjuvant therapy.

Conclusion/Discussion: Signet cell mucinous adenocarcinoma of the canal anal is a very rare colorectal neoplasia with a poor prognosis; surgery is still the main treatment with chemoradiation therapy in selected cases. Intestinal ostomies have their specific morbidities and many times we need to use all surgical arsenal available like the vacuum devices, which enables an adequate reconstruction of the abdominal wall, reducing the infectious complications and restoring the anatomy and the patient's quality of life.

Abdominal wall with cecostomy cranially, mucous fistula distally and chronic inflamation
Abdominal wall reconstruction using vacuum-assisted closure therapy and ileostomy repositioning