Additional words by Alexandra Thompson.
A bizarre condition causes a woman to grow “eyelash-like” hair in her mouth.
The unnamed woman first went to doctors at the University of Foggia in Italy when she was 19 in 2009.
Her “exceedingly rare” condition was diagnosed as polycystic ovary syndrome (PCOS), which often causes excessive hair growth on the face.
The hair seemed to vanish within months of her being treated with contraceptive pills to regulate her hormones, Live Science reported.
Six years later, the woman returned to the clinic, with hair in her gums.
Confessing she had stopped taking the contraception, the then 25-year-old also had hair growing from her chin and neck.
Doctors removed the hair and asked her to return soon after for a check-up, the journal Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology reported.
The woman only went back a year later, when she had even more hair protruding from her gums.
The exact cause of her unusual hair growth is unclear, with the doctors speculating it may be linked to PCOS.
Her condition may have eased had she continued to take the contraception, they added. It is unclear why she came off it.
How could PCOS trigger hair growth in the mouth?
PCOS is a common condition, affecting around one in five women in the UK, according to the NHS.
In the US, between 6% and 12% of women of a “reproductive age” have the syndrome, statistics from the Centers for Disease Control and Prevention show.
PCOS affects how a woman’s ovaries work, leading to irregular periods when the ovaries fail to regularly release an egg.
It also causes excessive production of the “male hormones” androgens, which include testosterone. This can lead to excess facial or body hair.
Nonetheless, the woman’s case is thought to be the first ever linking PCOS to oral hair growth.
Gum tissue may theoretically be capable of growing hair.
The tissue that forms the mouth during embryonic development comes from the same layer of cells that make up the skin, Live Science reported.
It is common for people to have sebaceous glands, which secrete an oily substance, in their mouth.
Hair growing in the mouth is rare, however, with just five cases ever reported, according to the Foggia doctors.