A 66-year-old in Hong Kong who lived his whole life as a man has only now learned he is - biologically, at least - a woman.
The unnamed patient visited the doctor in with a swollen abdomen but, according to the Hong Kong Medical Journal, doctors realised the he was female after they found the swelling came from a large cyst on an ovary.
The confusion stemmed from the coincidence of two rare genetic disorders: Turner syndrome, which affects girls and women who have only one X chromosome or are missing part of their second X chromosome, with characteristics including infertility and short stature - the patient was only 4'6''; and congenital adrenal hyperplasia, increasing male hormones and making the patient, who had a beard and a "micropenis", appear like a man.
In a study published on Monday, seven doctors from two of the city's hospitals wrote: "Were it not due to the huge ovarian cyst, his intriguing medical condition might never have been exposed."
The Chinese patient, who was born in Vietnam, grew up as an orphan. He was found to have no testes, a history of urinary leakage since childhood, and stopped growing after puberty at the age of 10.
The doctors said there have been only six cases where both genetic disorders have been reported in medical literature, and that the patient decided to continue "perceiving himself as having a male gender with the possible need of testosterone replacement," according to the journal.