Black hairy tongue syndrome (BHT) is a condition of the tongue in which the small bumps on the tongue 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 Xerostomia, also known as dry mouth, is dryness in the mouth, which may be associated with a change in the composition of saliva, or reduced salivary flow, or have no identifiable cause. This symptom is very common and is often seen as a side ef ...

(dry mouth),

soft diet A mechanical soft diet or edentulous diet or soft food(s) diet is a diet that involves only foods that are physically soft, with the goal of reducing or eliminating the need to chew the food. It is recommended for people who have difficulty che ...

, poor

oral hygiene Oral hygiene is the practice of keeping one's mouth clean and free of disease and other problems (e.g. bad breath) by regular brushing of the teeth (dental hygiene) and cleaning between the teeth. It is important that oral hygiene be carried out ...

and certain medications. Management is facilitated 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 (in front) 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 (intra-oral

halitosis Bad breath, also known as halitosis, is a symptom in which a noticeably unpleasant breath odour is present. It can result in anxiety among those affected. It is also associated with depression and symptoms of obsessive compulsive disorder. T ...

). The term "melanoglossia' is also used to refer to there being black discolorations on the tongue without "hairs", which are also harmless and unrelated to black hairy tongue.

Causes

The cause is uncertain, but it is thought to be caused by accumulation of epithelial squames and proliferation of chromogenic (i.e., color-producing) microorganisms. There may be an increase in

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, hor ...

production or a decrease in normal

desquamation Desquamation occurs when the outermost layer of a tissue, such as the skin, is shed. The term is . Physiologic desquamation Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratinocytes reside in ...

(shedding of surface epithelial cells). Many people with BHT are heavy smokers. Other possible associated factors are poor oral hygiene, general debilitation, hyposalivation (i.e., decreased salivary flow rate),

radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...

, overgrowth of fungal or bacterial organisms, and a soft diet. Occasionally, BHT may be caused by the use of antimicrobial medications (e.g.,

tetracycline Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including acne, cholera, brucellosis, plague, malaria, and syphilis. Common side effect ...

s), or oxidizing mouthwashes or

antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alu ...

s. A soft diet may be involved as normally food has an abrasive action on the tongue, which keeps the filiform papillae short.

Pellagra Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over ...

, a condition caused by niacin (vitamin B3) 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 (or betel chewing), some foods and beverages (e.g., coffee, tea or

liquorice Liquorice (British English) or licorice (American English) ( ; also ) is the common name of ''Glycyrrhiza glabra'', a flowering plant of the bean family Fabaceae, from the root of which a sweet, aromatic flavouring can be extracted. The liqu ...

), and certain medications (e.g.,

chlorhexidine Chlorhexidine (CHX) (commonly known by the salt forms chlorhexidine gluconate and chlorhexidine digluconate (CHG) or chlorhexidine acetate) is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize surg ...

, iron salts, or

bismuth subsalicylate Bismuth subsalicylate, sold generically as pink bismuth and under the brand names Pepto-Bismol and BisBacter, is an antacid medication used to treat temporary discomforts of the stomach and gastrointestinal tract, such as nausea, heartburn, in ...

(Pepto-Bismol)).

Diagnosis

Diagnosis is usually made on the clinical appearance without the need for a tissue

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a disea ...

. However, when biopsies have been taken, the

histologic Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

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 Hairy leukoplakia is a white patch on the side of the tongue with a corrugated or hairy appearance. It is caused by Epstein-Barr virus (EBV) and occurs usually in persons who are immunocompromised, especially those with human immunodeficiency v ...

, however the latter usually occurs on the sides of the tongue and is associated with an

opportunistic infection An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened imm ...

with

Epstein–Barr virus The Epstein–Barr virus (EBV), formally called ''Human gammaherpesvirus 4'', is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. It is ...

on a background immunocompromise (almost always

human immunodeficiency virus The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

infection but rarely other conditions which suppress the immune system).

Classification

Hairy tongue (lingua villosa) refers to a marked accumulation of

on the filiform papillae on the dorsal surface of the tongue, giving a hair-like appearance. Black tongue (lingua nigra) 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

of the hyperparakeratotic papillae. Keratolytic agents (chemicals to remove keratin) such as

podophyllin Podophyllum resin, also known as podophyllum or podophyllin, is a resin made from the roots of the American mandrake. It is used as a medication to treat genital warts and plantar warts, including in people with HIV/AIDS. It is not recommended i ...

are successful, but carry safety concerns. Other reported successful measures include

sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation ( Na+) and a bicarbonate anion ( HCO3− ...

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.

References

External links

{{Oral pathology Tongue disorders Conditions of the mucous membranes