Tail-like Congenital Duplication of Lower Extremity (Extra Leg or Vestigial Parasitic Twin)

Congenital duplication of lower extremity, either complete or incomplete is extremely rare. Only 26 cases had been reported till 2010, of which only 5 cases had feature of complete duplication. Theories have been proposed that the cause of this abnormality includes maternal factors like diabetes and usage of teratogenic drugs. Duplication of lower extremity may mimic that of vestigial parasitic twin; phenotypically, it appears as an individual with extra appendage or limbs. Vestigial parasitic twis are very rare comprising only 10% of all conjoined twins). Conjoined twin by itself is rare because the survival rate after birth is approximately 25%.

A 5-year old female patient came from a rural area of Ethiopia was referred to our hospital for radiological diagnosis and to assess the vascular supply. No family history of similar congenital abnormality was identified. No known history of chronic illness or maternal usage of teratogenic drugs was identified either.

A child with parasitic twin and complete duplication of lower limb is reported. Tail-like soft tissue was found arising from sacral area. CT scan findings confirmed the duplication of the lower limb bones. Fatty tissue was the major component of the soft tissue almost replacing the muscle. Reconstructed CT angiography images showed major arterial blood supply of the parasite limb. Surgical intervention was done successfully. This type of case is unusual. It is the rarest type of lower limb duplication.