Surgical excision of developmental retrorectal cysts: results with long-term follow-up from a single institution.

Developmental cysts are very rare lesions occurring in the retrorectal space, and include epidermoid, dermoid, tailgut cysts and teratomas. There is little information on their natural history and biologic behavior, although a recent paper reported a greater incidence of malignant transformation than previously thought. The diagnosis requires high-resolution imaging, and complete surgical excision is the treatment of choice. In this paper we analyzed short- and long-term results of surgical excision of six retrorectal developmental cysts observed at our institution over a period of 11 years. All patients were women, three were referred with an infected perineal fistula/pelvic abscess after having undergone drainage surgery elsewhere. In these three patients, excision was attempted through a trans-perineal approach, which was technically demanding and ultimately incomplete because of the intense surrounding inflammation. Multiple re-interventions were required for tumor recurrence, and two of them still present an occasional perineal discharge. In the other three patients, a trans-perineal or trans-anal route was employed according to tumor location, without any recurrence at a median follow-up of 118.5 months. Final pathologic diagnosis included five tailgut cysts and one teratoma. This paper shows that the treatment of developmental cysts may be very challenging, especially when they are associated with a concomitant fistula/abscess and are not correctly diagnosed at presentation. In our experience, healing was finally achieved in four patients out of six. All the lesions were benign, and no malignant transformation was observed during follow-up, even in tumors partially resected.