Successful removal of a massive retrorectal cystic hamartoma (tailgut cyst) using a combined paracoccygeal and myocutaneous gluteal flap approach

Abstract

We report on a surgical en bloc excision (using a combined paracoccygeal and myocutaneous gluteal flap approach) of a large retrorectal cystic hamartoma (tailgut cyst). A 65-year-old male was referred with a 2-year history of a painless swelling in his right buttock and thigh. The patient subsequently underwent magnetic resonance imaging (MRI), revealing a large trilobular cystic lesion arising from the retrorectal space (with no connection to the rectum), extending laterally into the right ischioanal fossa, and continuing into the right gluteus maximus muscle and posterior compartment of the right thigh (Fig. 1a). Surgical excision of the lesion without biopsy (to avoid seeding) was performed by the two senior authors (consultant colorectal/plastic surgeons). The patient was placed in the prone jack-knife position under general anesthesia. Initial dissection commenced in the posterior thigh to remove the caudal portion of the cyst, and then the incision was extended cranially to raise a right sided myocutaneous gluteal flap, based on the inferior gluteal artery pedicle (Fig. 1b). This allowed excellent access to the cystic lesion within the gluteus maximus muscle to facilitate removal as a whole en bloc specimen. The incision was then extended in the right paracoccygeal plane to remove the most proximal portion of the cystic lesion lying in the right ischioanal space and retrorectal space, undertaken with a finger in the rectum helping to increase the cystic lesion into the wound. The rectum was not breached during the dissection, and the cystic lesion was removed in its entirety. The cystic lesion was observed (as per the MRI findings) to consist of three interconnecting cystic chambers with a very thin wall, 30 cm in length in the largest dimension. Histological findings were consistent with the diagnosis of a retrorectal cystic hamartoma (tailgut cyst). The patient made an uneventful recovery in the early postoperative period, but developed some erythema and discharge from the wound at approximately a month after surgery which settled with conservative measures. At 3 months, he was back to his normal activities with no further wound problems. Retrorectal cystic hamartomas (also known as tailgut cysts) are rare congenital lesions thought to arise from the remnants of the embryonic post-anal primitive gut in utero. More common in females, the mean age of presentation is in the fifth decade [1]. Malignant change (up to 13 % in one series) [2] has been reported, and on this basis, surgical excision is advised, even if the cyst is not causing any symptoms [3]. Recurrences after surgical excision have been reported [1, 2, 4], but it is unclear whether or not these were related to incomplete excision at the initial surgery. Retrorectal cystic hamartomas are usually small, and in the largest series reported, the average size reported was 3.9 cm [5]. The maximum cyst size in the two largest case series was 25 cm and 15 cm. To our knowledge, we describe here the successful removal of the largest retrorectal cystic hamartoma reported in the literature. A variety of surgical strategies have been described for the excision of retrorectal cystic hamartomas tailored to the size and extension of the lesion, which include abdominal approaches for cysts extending into the pelvis and a number of posterior approaches [3]. Due to the unusual anatomical J. Stallard G. Bourke Department of Plastic, Reconstructive and Hand Surgery, The General Infirmary at Leeds, Leeds, UK