Black, hairy tongue developed after cancer treatment

Diffuse grey pigmentation of the face and tongue covered with brownish-black patches is shown in this photo. (BMJ Case Reports)

In an unusual case study, a woman developed a black and hairy tongue after cancer treatment.

The rare phenomenon was described in a new paper published in the peer-reviewed journal BMJ Case Reports last month.

Doctors were first alerted to the issue when a woman in her 60s presented to a health-care facility for the treatment of hepatitis B. While doctors were assessing her, they noticed that she had grey, mottled patches on her skin that had not been there when she previously was at the facility three months earlier.

Upon further examination, they discovered that she had a patch of black pigmentation covering much of her tongue, and the bumps on her tongue had become prominent and hair-like.

Her tongue didn’t just look different than usual — it was painful as well, she told doctors.

A photo of the reaction shows a woman with a grey cast to her skin sticking out her tongue to show that it had changed colour, with darkness spreading out from the centre of her tongue like a stain.

She was diagnosed with black hairy tongue (BHT), which is a rare but reversible condition in which the tongue bumps (papillae) elongate and there is discolouration on the surface of the tongue.

The cause? A recent change in her cancer medication, according to the case report.

The woman has a 14 month history of post-operative chemotherapy for cancer with liver metastases, the report said, which had been undergone at a different hospital. But in the last four months, her chemotherapy was switched to new medications: panitumumab with irinotecan and 5-fluorouracil.

Although these are common medications associated with cancer and chemotherapy, the woman was also prescribed 100mg/day of minocycline to prevent skin lesions that can be caused by panitumumab.

At first, doctors were uncertain what the source was, as it could have been either the minocycline or the panitumumab that caused her BHT and hyper-pigmentation.

Both have been linked to BHT before, although the link between antibiotics such as minocycline is clearer. The facial hyper-pigmentation separate from the BHT led doctors to lean more towards minocycline, as it can lead to skin discolouration, with a 3-15 per cent incidence rate as a side effect.

She was immediately taken off of minocycline, and was given trifluridine and tipiracil hydrochloride plus bevacizumab combination therapy instead. 

Her pigmentation and BHT had cleared up significantly at a check-in six weeks later, with the skin returned to a healthier tone and only a slight darkness remaining at the centre of the tongue.

According to the Mayo Clinic, BHT is a temporary and usually harmless oral condition in which the tongue takes on a “dark, furry appearance.” Part of the problem is a buildup of dead skin cells on the papillae, which can trap bacteria which exacerbates the discolouration. Possible causes include changes in the normal oral bacteria after antibiotic use, but BHT can also be caused by poor oral hygiene, overuse of mouthwashes with irritants such as peroxide, tobacco use and even eating too many soft foods that don’t allow dead skin cells to be sloughed off of the tongue due to friction.