Black hairy tongue | |
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Other names | Lingua villosa nigra [1] [2] or Melanoglossia. [3] |
A patient displaying characteristic dark bumps of black hairy tongue | |
Specialty | Dermatology |
Risk factors | Smoking, poor oral hygiene, soft diet |
Diagnostic method | Based on clinical appearance |
Differential diagnosis | Hairy leukoplakia |
Treatment | Reassurance |
Black hairy tongue syndrome (BHT [4] ) 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 (dry mouth), soft diet, poor oral hygiene and certain medications. Management is facilitated by improving oral hygiene, especially scraping or brushing the tongue. [5]
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. [6] Discoloration usually accompanies hairy tongue, and may be yellow, brown or black. [6] Apart from the appearance, the condition is typically asymptomatic, but sometimes people may experience a gagging sensation or a bad taste. [6] There may also be associated oral malodor (intra-oral halitosis). [6]
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. [7]
The cause is uncertain, [6] but it is thought to be caused by accumulation of epithelial squames and proliferation of chromogenic (i.e., color-producing) microorganisms. [8] There may be an increase in keratin production or a decrease in normal desquamation (shedding of surface epithelial cells). [6] Many people with BHT are heavy smokers. [6] Other possible associated factors are poor oral hygiene, [6] general debilitation, [6] hyposalivation (i.e., decreased salivary flow rate), [8] radiotherapy, [6] overgrowth of fungal or bacterial organisms, [6] and a soft diet. [8] Occasionally, BHT may be caused by the use of antimicrobial medications (e.g., tetracyclines), [8] or oxidizing mouthwashes or antacids. [6] 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 niacin (vitamin B3) deficiency, may cause a thick greyish fur to develop on the dorsal tongue, along with other oral signs. [9]
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), [8] some foods and beverages (e.g., coffee, tea or liquorice), [8] and certain medications (e.g., chlorhexidine, [8] iron salts, [8] or bismuth subsalicylate (Pepto-Bismol)). [10]
Diagnosis is usually made on the clinical appearance without the need for a tissue biopsy. [6] 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. [6]
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 (almost always human immunodeficiency virus infection but rarely other conditions which suppress the immune system). [6]
Hairy tongue (lingua villosa) refers to a marked accumulation of keratin on the filiform papillae on the dorsal surface of the tongue, giving a hair-like appearance. [6] 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. [6] 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. [8] Drug-induced black hairy tongue specifically refers to BHT that develops because of medication. [11] Black hairy tongue can also be caused by antibiotics e.g., (penicillins, cephalosporins, tetracyclines, clarithromycin and linezolid). [12]
Treatment is by reassurance, as the condition is benign, and then by correction of any predisposing factors. [6] 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. [8] This promotes desquamation of the hyperparakeratotic papillae. [6] Keratolytic agents (chemicals to remove keratin) such as podophyllin are successful, but carry safety concerns. [6] Other reported successful measures include sodium bicarbonate mouthrinses, eating pineapple, sucking on a peach stone and chewing gum. [8]
BHT is a benign condition, [6] [13] [14] but people who are affected may be distressed at the appearance and possible halitosis, and therefore treatment is indicated.
Hairy tongue occurs in about 0.5% of adults. [6] However, the prevalence is variable depending on the population studied. [11]
The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste buds housed in numerous lingual papillae. It is sensitive and kept moist by saliva and is richly supplied with nerves and blood vessels. The tongue also serves as a natural means of cleaning the teeth. A major function of the tongue is the enabling of speech in humans and vocalization in other animals.
A mouth ulcer (aphtha), or sometimes called a Canker sore, is an ulcer that occurs on the mucous membrane of the oral cavity. Mouth ulcers are very common, occurring in association with many diseases and by many different mechanisms, but usually there is no serious underlying cause. Rarely, a mouth ulcer that does not heal may be a sign of oral cancer. These ulcers may form individually or multiple ulcers may appear at once. Once formed, an ulcer may be maintained by inflammation and/or secondary infection.
Taste buds are clusters of taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the cheek, and epiglottis. These structures are involved in detecting the five elements of taste perception: saltiness, sourness, bitterness, sweetness and savoriness (umami). A popular assumption assigns these different tastes to different regions of the tongue; in actuality, these tastes can be detected by any area of the tongue. Via small openings in the tongue epithelium, called taste pores, parts of the food dissolved in saliva come into contact with the taste receptors. These are located on top of the taste receptor cells that constitute the taste buds. The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via the seventh, ninth and tenth cranial nerves.
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.
Oral candidiasis (Acute pseudomembranous candidiasis), which is also known as oral thrush, among other names, is candidiasis that occurs in the mouth. That is, oral candidiasis is a mycosis (yeast/fungal infection) of Candida species on the mucous membranes of the mouth.
Oral leukoplakia is a potentially malignant disorder affecting the oral mucosa. It is defined as "essentially an oral mucosal white lesion that cannot be considered as any other definable lesion." Oral leukoplakia is a white patch or plaque that develops in the oral cavity and is strongly associated with smoking. Leukoplakia is a firmly attached white patch on a mucous membrane which is associated with increased risk of cancer. The edges of the lesion are typically abrupt and the lesion changes with time. Advanced forms may develop red patches. There are generally no other symptoms. It usually occurs within the mouth, although sometimes mucosa in other parts of the gastrointestinal tract, urinary tract, or genitals may be affected.
Keratin 6A is one of the 27 different type II keratins expressed in humans. Keratin 6A was the first type II keratin sequence determined. Analysis of the sequence of this keratin together with that of the first type I keratin led to the discovery of the four helical domains in the central rod of keratins. In humans Keratin 6A is encoded by the KRT6A gene.
Xerostomia, also known as dry mouth, is a subjective complaint of 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.
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 virus infection/acquired immunodeficiency syndrome (HIV/AIDS). The white lesion, which cannot be scraped off, is benign and does not require any treatment, although its appearance may have diagnostic and prognostic implications for the underlying condition.
Stomatitis is inflammation of the mouth and lips. It refers to any inflammatory process affecting the mucous membranes of the mouth and lips, with or without oral ulceration.
Glossitis can mean soreness of the tongue, or more usually inflammation with depapillation of the dorsal surface of the tongue, leaving a smooth and erythematous (reddened) surface,. In a wider sense, glossitis can mean inflammation of the tongue generally. Glossitis is often caused by nutritional deficiencies and may be painless or cause discomfort. Glossitis usually responds well to treatment if the cause is identified and corrected. Tongue soreness caused by glossitis is differentiated from burning mouth syndrome, where there is no identifiable change in the appearance of the tongue, and there are no identifiable causes.
The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed lamina propria. The oral cavity has sometimes been described as a mirror that reflects the health of the individual. Changes indicative of disease are seen as alterations in the oral mucosa lining the mouth, which can reveal systemic conditions, such as diabetes or vitamin deficiency, or the local effects of chronic tobacco or alcohol use. The oral mucosa tends to heal faster and with less scar formation compared to the skin. The underlying mechanism remains unknown, but research suggests that extracellular vesicles might be involved.
Geographic tongue, also known by several other terms, is a condition of the mucous membrane of the tongue, usually on the dorsal surface. It is a common condition, affecting approximately 2–3% of the general population. It is characterized by areas of smooth, red depapillation which migrate over time. The name comes from the map-like appearance of the tongue, with the patches resembling the islands of an archipelago. The cause is unknown, but the condition is entirely benign, and there is no curative treatment. Uncommonly, geographic tongue may cause a burning sensation on the tongue, for which various treatments have been described with little formal evidence of efficacy.
Burning mouth syndrome (BMS) is a burning, tingling or scalding sensation in the mouth, lasting for at least four to six months, with no underlying known dental or medical cause. No related signs of disease are found in the mouth. People with burning mouth syndrome may also have a subjective xerostomia, paraesthesia, or an altered sense of taste or smell.
Keratin 6B is a type II cytokeratin, one of a number of isoforms of keratin 6. It is found with keratin 16 and/or keratin 17 in the hair follicles, the filiform papillae of the tongue and the epithelial lining of oral mucosa and esophagus. This keratin 6 isoform is thought be less abundant than the closely related keratin 6A protein. Mutations in the gene encoding this protein have been associated with pachyonychia congenita, an inherited disorder of the epithelial tissues in which this keratin is expressed, particularly leading to structural abnormalities of the nails, the epidermis of the palms and soles, and oral epithelia. Keratin 6B is associated with the PC-K6B subtype of pachyonychia congenita.
Tongue diseases can be congenital or acquired, and are multiple in number. Considered according to a surgical sieve, some example conditions which can involve the tongue are discussed below. Glossitis is a general term for tongue inflammation, which can have various etiologies, e.g. infection.
Median rhomboid glossitis is a condition characterized by an area of redness and loss of lingual papillae on the central dorsum of the tongue, sometimes including lesions of the tongue and palate. It is seen in patients using inhaled steroids and smokers, and is usually a kind of chronic atrophic oral candidiasis, but hematinic deficiency and diabetes should be excluded.
Oral pigmentation is asymptomatic and does not usually cause any alteration to the texture or thickness of the affected area. The colour can be uniform or speckled and can appear solitary or as multiple lesions. Depending on the site, depth, and quantity of pigment, the appearance can vary considerably.
A mouth assessment is performed as part of a patient's health assessment. The mouth is the beginning of the digestive system and a substantial part of the respiratory tract. Before an assessment of the mouth, patient is sometimes advised to remove any dentures. The assessment begins with a dental-health questionnaire, including questions about toothache, hoarseness, dysphagia, altered taste or a frequent sore throat, current and previous tobacco use and alcohol consumption and any sores, lesions or bleeding of the gums.
Lingual papillae are small structures on the upper surface of the tongue that give it its characteristic rough texture. The four types of papillae on the human tongue have different structures and are accordingly classified as circumvallate, fungiform, filiform, and foliate. All except the filiform papillae are associated with taste buds.