[Laparoscopic Abdominoperineal Resection with the Trans-Perineal Approach for Anal Canal Cancer in a Patient with Situs Inversus Totalis-A Case Report].

Situs inversus totalis(SIT)is a rare congenital condition that causes complete transposition of thoracic and abdominal viscera. Due to associated anatomical abnormalities and low frequency, surgery for affected patients is considered to be difficult. A 72-year-old man was referred to our hospital with a chief complaint of narrow stools. The diagnosis was anal canal cancer(cT1bN0M0)accompanied by SIT. A trans-perineal minimally invasive surgical procedure with laparoscopic abdominoperineal resection(Tp-APR)was performed. When mobilizing the sigmoid colon, the surgeon changed their position in consideration of anatomical abnormalities. On the other hand, manipulation around the rectum was possible using the same technique as in patients with normal anatomy. The postoperative course was uneventful, and he had no recurrence 18 months after surgery. This is the first case that showed Tp-APR for anal canal cancer with SIT performed safely and feasibly. Preoperative simulation of associated abnormal anatomical structures is considered crucial for a case of SIT.