Delayed presentation of a heteropagus (parasitic) twin: a case report of a 17-year-old patient.

Conjoined twins are rare, but well-described, anomalies. The heteropagus (parasitic) variant, in which there is a fully functioning autosite and a partially formed parasite, is even more rare. Typically, patients with this condition are discovered and treated as neonates or infants. We present an unusual case of an ischiopagus patient presenting at 17 years of age, which appears to be the oldest recorded presentation for surgery of a heteropagus twin in the English literature. The patient had two additional developed lower extremities along with two additional rudimentary upper extremities. The challenges and lessons learned from this rare and complex surgery are discussed.