There are no symptoms associated with the lesion itself, although many and varied symptoms and signs may be associated with the underlying cause of immunosuppression. The lesion is a white patch, which almost exclusively occurs on the lateral surfaces of the tongue, although rarely it may occur on the buccal mucosa, soft palate, pharynx or esophagus. The lesion may grow to involve the dorsal surface of the tongue. The texture is vertically corrugated ("hairy") or thickly furrowed and shaggy in appearance.

In a classification of the oral lesions in HIV disease, OHL is grouped as "lesions strongly associated with HIV infection" (group I). It could also be classed as an opportunistic, viral disease. Hairy leukoplakia occurs on the tongue and has a similar name to hairy tongue, but these are separate conditions with different causes.

Erythematous (atrophic) candidiasis is when the condition appears as a red, raw-looking lesion. Some sources consider denture-related stomatitis, angular stomatitis, median rhombiod glossitis, and antiobiotic-induced stomatitis as subtypes of erythematous candidiasis, since these lesions are commonly erythematous/atrophic. It may precede the formation of a pseudomembrane, be left when the membrane is removed, or arise without prior pseudomembranes. Some sources state that erythematous candidiasis accounts for 60% of oral candidiasis cases. Where it is associated with inhalation steroids (often used for treatment of asthma), erythematous candidiasis commonly appears on the palate or the dorsum of the tongue. On the tongue, there is loss of the lingual papillae (depapillation), leaving a smooth area.

Acute erythematous candidiasis usually occurs on the dorsum of the tongue in persons taking long term corticosteroids or antibiotics, but occasionally it can occur after only a few days of using a topical antibiotic. This is usually termed "antibiotic sore mouth", "antibiotic sore tongue", or "antibiotic-induced stomatitis" because it is commonly painful as well as red.

Chronic erythematous candidiasis is more usually associated with denture wearing (see denture-related stomatitis).

In the context of lesions of the mucous membrane lining of the bladder, leukoplakia is a historic term used to describe a visualized white patch which histologically represents keratinization in an area of squamous metaplasia. The symptoms may include frequency, suprapubic pain (pain felt above the pubis), hematuria (blood in the urine), dysuria (difficult urination or pain during urination), urgency, and urge incontinence. The white lesion may be seen during cystoscopy, where it appears as a whitish-gray or yellow lesion, on a background of inflamed urothelium and there may be floating debris in the bladder. Leukoplakia of the bladder may undergo cancerous changes, so biopsy and long term follow up are usually indicated.

This refers to a group of rare syndromes characterized by chronic candidal lesions on the skin, in the mouth and on other mucous membranes (i.e., a secondary oral candidiasis). These include Localized chronic mucocutaneous candidiasis, diffuse mucocutaneous candidiasis (Candida granuloma), candidiasis–endocrinopathy syndrome and candidiasis thymoma syndrome. About 90% of people with chronic mucocutaneous candidiasis have candidiasis in the mouth.

Most cases of leukoplakia cause no symptoms, but infrequently there may be discomfort or pain. The exact appearance of the lesion is variable. Leukoplakia may be white, whitish yellow or grey. The size can range from a small area to much larger lesions. The most common sites affected are the buccal mucosa, the labial mucosa and the alveolar mucosa, although any mucosal surface in the mouth may be involved. The clinical appearance, including the surface texture and color, may be homogenous or non-homogenous (see: classification). Some signs are generally associated with a higher risk of cancerous changes (see: prognosis).

Leukoplakia may rarely be associated with esophageal carcinoma.

Oral lichen planus (also termed "oral mucosal lichen planus"), is a form of mucosal lichen planus, where lichen planus involves the oral mucosa, the lining of the mouth. This may occur in combination with other variants of lichen planus. Six clinical forms of oral lichen planus are recognized:

- "Reticular", the most common presentation of oral lichen planus, is characterised by the net-like or spider web-like appearance of lacy white lines, oral variants of Wickham's straiae. This is usually asymptomatic.

- "Erosive/ulcerative", the second most common form of oral lichen planus, is characterised by oral ulcers presenting with persistent, irregular areas of redness, ulcerations and erosions covered with a yellow slough. This can occur in one or more areas of the mouth. In 25% of people with erosive oral lichen planus, the gums are involved, described as desquamative gingivitis (a condition not unique to lichen planus). This may be the initial or only sign of the condition.

- "Papular," with white papules.

- "Plaque-like" appearing as a white patch which may resemble leukoplakia.

- "Atrophic," appearing as areas. Atrophic oral lichen planus may also manifest as desquamative gingivitis.

- "Bullous," appearing as fluid-filled vesicles which project from the surface.

These types often coexist in the same individual. Oral lichen planus tends to present bilaterally as mostly white lesions on the inner cheek, although any mucosal site in the mouth may be involved. Other sites, in decreasing order of frequency, may include the tongue, lips, gingivae, floor of the mouth, and very rarely, the palate.

Generally, oral lichen planus tends not to cause any discomfort or pain, although some people may experience soreness when eating or drinking acidic or spicy foodstuffs or beverages. When symptoms arise, they are most commonly associated with the atrophic and ulcerative subtypes. These symptoms can include a burning sensation to severe pain. Lichen planus, particularly when concomitant oral or genital lesions occur, significantly affects patients’ quality of life.

Although often the terms "erythroplasia" and "erythroplakia" are used synonymously, some sources distinguish them, stating that the latter is maccular (flat) while the former is papular (bumpy).

Erythroplakia of the genital mucosae is often referred to as erythroplasia of Queyrat.

The most common areas in the mouth where erythroplakia is found are the floor of the mouth, buccal vestibule, the tongue, and the soft palate. It appears as a red macule or plaque with well-demarcated borders. The texture is characterized as soft and velvety. An adjacent area of leukoplakia may be found along with the erythroplakia.

Erythroplasia may also occur on the laryngeal mucosa, or the anal mucosa.

Lichen planus affecting mucosal surfaces may have one lesion or be multifocal. Examples of lichen planus affecting mucosal surfaces include:

- "Esophageal lichen planus", affecting the esophageal mucosa. This can present with difficulty or pain when swallowing due to oesophageal inflammation, or as the development of an esophageal stricture. It has also been hypothesized that it is a precursor to squamous cell carcinoma of the esophagus.

- "Genital lichen planus," which may cause lesions on the glans penis or skin of the scrotum in males, and the vulva or vagina in females. Symptoms may include lower urinary tract symptoms associated with stenosis of the urethra, painful sexual intercourse, and itching. In females, "Vulvovaginal-gingival syndrome," is severe and distinct variant affecting the vulva, vagina, and gums, with complications including scarring, vaginal stricture formation, or vulva destruction. The corresponding syndrome in males, affecting the glans penis and gums, is the "peno-gingival syndrome". It is associated with HLA-DQB1.

LS can occur without symptoms. White patches on the LS body area, itching, pain, pain during sex (in genital LS), easier bruising, cracking, tearing and peeling, and hyperkeratosis are common symptoms in both men and women. In women, the condition most commonly occurs on the vulva and around the anus with ivory-white elevations that may be flat and glistening.

In males, the disease may take the form of whitish patches on the foreskin and its narrowing (preputial stenosis), forming an "indurated ring", which can make retraction more difficult or impossible. In addition there can be lesions, white patches or reddening on the glans. In contrast to women, anal involvement is less frequent. Meatal stenosis, making it more difficult or even impossible to urinate, may also occur.

On the non-genital skin, the disease may manifest as porcelain-white spots with small visible plugs inside the orifices of hair follicles or sweat glands on the surface. Thinning of the skin may also occur.

Perforating folliculitis is a skin condition in humans characterized by discrete follicular keratotic eruptions involving mainly the hairy parts of the extremities.

Human immunodeficiency virus salivary gland disease (abbreviated to HIV-SGD, and also termed HIV-associated salivary gland disease), is swelling of the salivary glands and/or xerostomia in individuals infected with human immunodeficiency virus.

There are many other conditions that are similar in appearance and must be ruled out before a diagnosis of erythroplakia is made (see table). Sometimes, a diagnosis is delayed for up to two weeks in order to see if the lesion spontaneously regresses on its own or if another cause can be found. Erythroplakia frequently is associated with dysplasia, and is thus a precancerous lesion.

HIV-SGD may be the presenting sign of HIV infection. There may also be xerophthalmia (dry eyes) and arthralgia (joint pain), similar to Sjögren syndrome.

In health, the dorsal surface of the tongue is covered in tuft like projections called lingual papillae (some of which are associated with taste buds), which give the tongue an irregular surface texture and a white-pink color. Geographic tongue is characterized by areas of atrophy and depapillation (loss of papillae), leaving an erythematous (darker red) and smoother surface than the unaffected areas. The depapillated areas are usually well demarcated, and bordered by a slightly raised, white, yellow or grey, serpiginous (snaking) peripheral zone. A lesion of geographic tongue may start as a white patch before the depapillation occurs. In certain cases there may be only one lesion, but this is uncommon; the lesions will typically occur in multiple locations on the tongue and coalesce over time to form the typical map-like appearance. The lesions usually change in shape, size and migrate to other areas, sometimes within hours. The condition may affect only part of the tongue, with a predilection for the tip and the sides of the tongue, or the entire dorsal surface at any one time. The condition goes through periods of remission and relapse. Loss of the white peripheral zone is thought to signify periods of mucosal healing.

There are usually no symptoms other than the unusual appearance of the tongue, but in some cases persons may experience pain or burning e.g. when eating hot, acidic, spicy or other kinds of foods (e.g. cheese, tomatoes, fruit). Where there is a burning symptom, other causes of a burning sensation on the tongue are considered, such as oral candidiasis.

Distress due to the discomfort and pain of Lichen Sclerosus is normal, as are concerns with self-esteem and sex. Counseling can help.

According to the National Vulvodynia Association, which also supports women with Lichen Sclerosus, vulvo-vaginal conditions can cause feelings of isolation, hopelessness, low self-image, and much more. Some women are unable to continue working or have sexual relations and may be limited in other physical activities. Depression, anxiety, and even anger are all normal responses to the ongoing pain LS patients suffer from.

In the initial phase of the disease, the mucosa feels leathery with palpable fibrotic bands. In the advanced stage the oral mucosa loses its resiliency and becomes blanched and stiff. The disease is believed to begin in the posterior part of the oral cavity and gradually spread outward.

Other features of the disease include:

- Xerostomia

- Recurrent ulceration

- Pain in the ear or deafness

- Nasal intonation of voice

- Restriction of the movement of the soft palate

- A budlike shrunken uvula

- Thinning and stiffening of the lips

- Pigmentation of the oral mucosa

- Dryness of the mouth and burning sensation

- Decreased mouth opening and tongue protrusion

There is a diffuse, gray-white, milky opalescent appearance of the mucosa which usually occurs bilaterally on the buccal mucosa. Less often, the labial mucosa, the palate or the floor of mouth may be affected. The surface of the area is folded, creating a wrinkled, white streaked lesion. Apart from the appearance, the lesion is entirely asymptomatic.

The palate may appear gray or white and contain many papules or nodules that are slightly elevated with red dots in their center. These red dots represent the ducts of minor salivary glands which have become inflamed by heat. The condition is painless. If a denture is normally worn while smoking, then the mucosa underneath the denture appears unaffected by the condition. In severe cases, the mucosa may show fissuring and develop a "dried lake bed" appearance. Other changes associated with tobacco use may be evident such as brown or black extrinsic staining of teeth from tar and other components of tobacco smoke.

Aphthous stomatitis is a common condition characterized by the repeated formation of benign and non-contagious mouth ulcers (aphthae) in otherwise healthy individuals. The informal term canker sores is also used, mainly in North America, although this may also refer to any mouth ulcer.

The cause is not completely understood, but involves a T cell-mediated immune response triggered by a variety of factors. Different individuals have different triggers, which may include nutritional deficiencies, local trauma, stress, hormonal influences, allergies, or genetic predisposition.

These ulcers occur periodically and heal completely between attacks. In the majority of cases, the individual ulcers last about 7–10 days, and ulceration episodes occur 3–6 times per year. Most appear on the non-keratinizing epithelial surfaces in the mouth (i.e. anywhere except the attached gingiva, the hard palate and the dorsum of the tongue), although the more severe forms, which are less common, may also involve keratinizing epithelial surfaces. Symptoms range from a minor nuisance to interfering with eating and drinking. The severe forms may be debilitating, even causing weight loss due to malnutrition.

The condition is very common, affecting about 20% of the general population to some degree. The onset is often during childhood or adolescence, and the condition usually lasts for several years before gradually disappearing. There is no cure, and treatments aim to manage pain, reduce healing time and reduce the frequency of episodes of ulceration. The term is from meaning "mouth ulcer".

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).

Persons with aphthous stomatitis have no detectable systemic symptoms or signs (i.e., outside the mouth). Generally, symptoms may include prodromal sensations such as burning, itching, or stinging, which may precede the appearance of any lesion by some hours; and pain, which is often out of proportion to the extent of the ulceration and is worsened by physical contact, especially with certain foods and drinks (e.g., if they are acidic). Pain is worst in the days immediately following the initial formation of the ulcer, and then recedes as healing progresses. If there are lesions on the tongue, speaking and chewing can be uncomfortable, and ulcers on the soft palate, back of the throat, or esophagus can cause painful swallowing. Signs are limited to the lesions themselves.

Ulceration episodes usually occur about 3–6 times per year. However, severe disease is characterized by virtually constant ulceration (new lesions developing before old ones have healed) and may cause debilitating chronic pain and interfere with comfortable eating. In severe cases, this prevents adequate nutrient intake leading to malnutrition and weight loss.

Aphthous ulcers typically begin as erythematous macules (reddened, flat area of mucosa) which develop into ulcers that are covered with a yellow-grey fibrinous membrane that can be scraped away. A reddish "halo" surrounds the ulcer. The size, number, location, healing time, and periodicity between episodes of ulcer formation are all dependent upon the subtype of aphthous stomatitis.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

Black hairy tongue (BHT, also termed lingua villosa nigra) 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 (dry mouth), soft diet, poor oral hygiene and certain medications. Management is by improving oral hygiene, especially scraping or brushing the tongue.

Stomatitis nicotina (also known as nicotine stomatitis, nicotinic stomatitis, nicotine palatinus, stomatitis palatini, leukokeratosis nicotina palate, palatal leukokeratosis, smoker's keratosis, smoker's palate, and smoker's patches), is a diffuse white patch on the hard palate, usually caused by tobacco smoking, usually pipe or cigar smoking. It is painless, and it is caused by a response of the palatal oral mucosa to chronic heat. A more pronounced appearance can occur with reverse smoking, sometimes distinguished from stomatitis nicotina by the term reverse smoker's keratosis. While stomatitis nicotina that is caused by heat is not a premaligant condition (i.e. it does not carry an increased risk of transformation to oral cancer), the condition that is caused by reverse smoking is premalignant.