A 66-year-old who lived his whole life as a man was given a surprising diagnosis after visiting the doctor in Hong Kong with a swollen abdomen - he was a woman.

Doctors realised the patient was female after they found the swelling came from a large cyst on an ovary, the Hong Kong Medical Journal reported.

The condition was the result of two rare genetic disorders.

The subject had Turner syndrome, which affects girls and women and results from a problem with the chromosomes, with characteristics including infertility and short stature.

But he also had congenital adrenal hyperplasia, increasing male hormones and making the patient, who had a beard and a "micropenis", appear like a man.