PETALING JAYA: Surgeons at Sultan Abdul Halim Hospital in Sungai Petani have removed a dead foetus which had its own hair and penis from the stomach of a 15-year-old boy.

The foetus, which weighed 1.6kg and had deformed limbs, had been leaching into his blood supply and feeding off him, The Daily Mail of UK reported yesterday, citing the BMJ Case Reports.

BMJ Case Reports is an educational resource offering a high volume of cases in all disciplines for healthcare professionals, researchers and others to find clinically important information on common and rare conditions.

The unnamed patient had been plagued with unbearable stomach pain and bloating since he was born. His conditions had doctors baffled.

However, the source of his discomfort was discovered when the teenager was taken to the Sultan Abdul Halim Hospital.

Doctors initially thought he had a tumour. CT scans were conducted on the boy when they felt a tender, hard mass over the central part of his abdomen.

The scans revealed a "huge intra-abdominal mass" that was 23.8cm long, which showed the development of a spine.

Doctors found the boy's unborn twin which was leaching and feeding off him. The malformed foetus had long hair, developed male genitalia and skin covering its body when it was taken out.

BMJ Case Reports said the twin was a non-viable baby, meaning it wasn't capable of living independently. It had no mouth, umbilical cord or placenta.

"Components in favour of a fetus that were seen within the mass include a deformed skull, vertebral body and long bones," the report read.

The unborn baby was returned to the family for a private funeral at the mother's request.

The team of doctors, led by Dr Rashide Yaacob, said the complete removal of the dead twin is crucial.

"There is a possibility of malignant recurrence if any of the tissue is not completely excised," he said. "The operation to remove the foetus in foetu is a challenging operation as the mass is highly vascular with multiple feeding vessels.

"The big size of the foetus has made surgery more difficult as there is a high possibility of injuring surrounding structures."

The patient has since recovered from the undated operation.