Successful separation of the conjoined thecal sac with an epidermal cyst in pygopagus twins.

Pygopagus conjoined twins are very rare, and half of all pygopagus twins have other anomalies. This report describes the successful surgical separation of pygopagus twins who had a conjoined thecal sac and an epidermal cyst. Meticulous preoperative planning, development of a model simulator, multispecialty teamwork, and a staged surgery contributed to a successful outcome.