Black hairy tongue refers to a condition of the tongue where the filiform
papillae elongate with black or brown discoloration, giving a black and hairy
appearance. The appearance may be alarming, but it is a harmless
condition. Predisposing factors include smoking, xerostomia, soft diet, poor
oral hygiene and certain medications. Management is by improving oral hygiene,
especially scraping or brushing the tongue.
Signs and symptoms Hairy tongue largely occurs in the
central part of the dorsal tongue, just anterior of the circumvallate papillae,
although sometimes the entire dorsal surface may be involved. Discoloration
usually accompanies hairy tongue, and may be yellow, brown or black. Apart
from the appearance, the condition is typically asymptomatic, but sometimes
people may experience a gagging sensation or a bad taste. There may also
be associated oral malodor. Causes
The cause is uncertain, but it is thought to be caused by accumulation of
epithelial squames and proliferation of chromogenic micro-organisms. There may
be an increase in keratin production or a decrease in normal desquamation. Many
people with BHT are heavy smokers. Other possible associated factors are poor
oral hygiene, general debilitation, hyposalivation, radiotherapy, overgrowth
of fungal or bacterial organisms, and a soft diet. Occasionally, BHT may be
caused by the use of antimicrobial medications e.g. tetracyclines, or
oxidizing mouthwashes or antacids. A soft diet may be involved as normally
food has an abrasive action on the tongue, which keeps the filiform
papillae short. Pellagra, a condition caused by a vitamin deficiency, may
cause a thick greyish fur to develop on the dorsal tongue, along with other oral
signs. Transient surface discoloration of the
tongue and other soft tissues in the mouth can occur in the absence of hairy
tongue. Causes include smoking, some foods and beverages, and certain
medications e.g. chlorhexidine, iron salts, or bismuth subsalicylate.
Diagnosis Diagnosis is usually made on the
clinical appearance without the need for a tissue biopsy. However, when biopsies
have been taken, the histologic appearance is one of marked elongation
and hyperparakeratosis of the filiform papillae and numerous bacteria growing
on the epithelial surface. Hairy tongue may be confused with hairy
leukoplakia, however the latter usually occurs on the sides of the tongue and is
associated with an opportunistic infection with Epstein-Barr virus on a
background immunocompromise. = Classification=
Hairy tongue refers to a marked accumulation of keratin on the filiform
papillae on the dorsal surface of the tongue, giving a hair-like appearance.
Black tongue refers to a black discoloration of the tongue, which may
or may not be associated with hairy tongue. However, the elongated papillae
of hairy tongue usually develop discoloration due to growth of pigment
producing bacteria and staining from food. Hence the term black hairy tongue,
although hairy tongue may also be discolored yellow or brown. Transient,
surface discoloration that is not associated with hairy tongue can be
brushed off. Drug-induced black hairy tongue specifically refers to BHT that
develops because of medication. Treatment
Treatment is by reassurance, as the condition is benign, and then by
correction of any predisposing factors. This may be cessation of smoking or
cessation/substitution of implicated medications or mouthwashes. Generally
direct measures to return the tongue to its normal appearance involve improving
oral hygiene, especially scraping or brushing the tongue before sleep. This
promotes desquamation of the hyperparakeratotic papillae. Keratolytic
agents such as podophyllin are successful, but carry safety concerns.
Other reported successful measures include sodium bicarbonate mouthrinses,
eating pineapple, sucking on a peach stone and chewing gum.
Prognosis BHT is a benign condition, but people
who are affected may be distressed at the appearance and possible halitosis,
and therefore treatment is indicated. Epidemiology
Hairy tongue occurs in about 0.5% of adults. However, the prevalence is
variable depending on the population studied.
History In 1937, Conrad Elvehjem showed the
vitamin niacin cured pellagra in dogs, which was manifested as black tongue.
References