Gardasil 6 is an HPV vaccine aimed at preventing cervical cancers and genital warts. Gardasil is designed to prevent infection with HPV types 16, 18, 6, and 11. HPV types 16 and 18 currently cause about 70% of cervical cancer cases, and also cause some vulvar, vaginal, penile and anal cancers. HPV types 6 and 11 are responsible for 90% of documented cases of genital warts.

Gardasil 9, approved in 2014 protects against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58.

HPV vaccines do not currently protect against the virus strains responsible for plantar warts (verrucas).

The virus is relatively hardy and immune to many common disinfectants. Exposure to 90% ethanol for at least 1 minute, 2% glutaraldehyde, 30% Savlon, and/or 1% sodium hypochlorite can disinfect the pathogen.

The virus is resistant to drying and heat, but killed by and ultraviolet radiation.

HPV is spread by direct and indirect contact from an infected host. Avoiding direct contact with infected surfaces such as communal changing rooms and shower floors and benches, avoiding sharing of shoes and socks and avoiding contact with warts on other parts of the body and on the bodies of others may help reduce the spread of infection. Infection is less common among adults than children.

As all warts are contagious, precautions should be taken to avoid spreading them. Recommendations include:

- cover them with an adhesive bandage while swimming

- wear flip-flops when using communal showers

- should not share towels.

Plantar warts are not prevented by inoculation with HPV vaccines because the warts are caused by different strains of HPV. Gardasil protects against strains 6, 11, 16, and 18, and Cervarix protects against 16 and 18, whereas plantar warts are caused by strains 1, 2, 4, and 63.

Seborrheic keratosis is the most common benign skin tumor. Incidence increases with age. There is less prevalence in people with darker skin. In large-cohort studies, 100% of the patients over age 50 had at least one seborrheic keratosis. Onset is usually in middle age, although they are common in younger patients too—found in 12% of 15-year-olds to 25-year-olds—making the term "senile keratosis" a misnomer.

A number of treatments have been found to be effective. A 2012 review of different treatments for skin warts in otherwise healthy people concluded modest benefit from salicylic acid and cryotherapy appears similar to salicylic acid.

Periungual warts are warts that cluster around the fingernail or toenail. They appear as thickened, fissured cauliflower-like skin around the nail plate. Periungual warts often cause loss of the cuticle and paronychia. Nail biting increases susceptibility to these warts.

Warts of this kind often cause damage to the nail either by lifting the nail from the skin or causing the nail to partially detach. If they extend under the nail, then the patient may suffer pain as a result. Sometimes periungual wart infections resemble the changes that are found in onychomycosis. In worst cases, if the infection causes injury or damage to the nail matrix, deformity in the nail may become permanent.

As with other wart types, a number of treatments are available, including laser therapy, cryotherapy, salicylic acid, and other topical treatments.

A study in Sweden showed that 21.5% of smokers and 3% of nonsmokers (genetic pigmentation or unknown cause) had lesions that could be classified as an oral melanin pigmentation. A gingival melanin index in 4 degrees was established. Already with a consumption of 1-3 cigarettes a day 9.3% of all 20.333 examined showed a smoker's melanosis. Pipe smokers had smoker's melanosis in 16.8%. One year after the start of cigarette smoking a clinically visible smoker's melanosis could be seen in 12.3% of women, and 17% among men.

In cigarette smokers who quit smoking, the number of individuals with smoker's melanosis becomes slowly less frequent after 2–3 months, but can still be seen in a few former smokers three years after smoking stop.

Although clinically visible genetic melanin pigmentations in the mouth are present in several ethnic groups all over the world, more mucosal areas will be melanin-pigmentet if tobacco products are used. Smoker's melanosis is found in India, Italy, Japan, Nigeria, Sweden, Turkey, USA, and several other countries.

Smoker's melanosis is expected to be found also in other tissue surfaces exposed to tobacco and tobacco smoke, for instance lips and in skin of the fingers holding the cigarette. Future studies will also show if the use of tobacco exaggerates the pigmentation of skin.

No treatment of seborrheic keratoses is necessary, except for aesthetic reasons. Since a slightly increased risk of localized infection caused by picking at the lesion has been described, if a lesion becomes itchy or irritated by clothing or jewelry, a surgical excision is generally recommended.

Small lesions can be treated with light electrocautery. Larger lesions can be treated with electrodesiccation and curettage, shave excision, or cryosurgery. When correctly performed, removal of seborrheic keratoses will not cause much visible scarring except in persons with dark skin tones.

Ultraviolet light from the sun causes premature aging of the skin and skin damage that can lead to melanoma. Some scientists hypothesize that overexposure to UV, including excessive sunlight, may play a role in the formation of acquired moles. However, more research is needed to determine the complex interaction between genetic makeup and overall exposure to ultraviolet light. Some strong indications that this is so (but falling short of proof), are:

- The relative lack of moles on the buttocks of people with dysplastic nevi.

- Freckles (spots of melanin on the skin, and distinct from moles) are known to be influenced by sunlight.

Studies have found that sunburns and too much time in the sun can increase the risk factors for melanoma. This is "in addition to" those who have dysplastic nevi being at higher risk of this cancer (the uncertainty is in regard to acquiring "benign" moles). To prevent and reduce the risk of melanoma caused by UV radiation, the American Academy of Dermatology and the National Cancer Institute recommends staying out of the sun between 10 a.m. and 4 p.m. standard time (or whenever one's shadow is shorter than one's height). The National Cancer Institute also recommends wearing long sleeves and trousers, hats with a wide brim, sunscreens, and sunglasses that have UV-deflecting lenses.

Verruca plana, also known as a "flat wart", is a reddish-brown or flesh-colored, slightly raised, flat-surfaced, well-demarcated papule of 2 to 5 mm in diameter. Upon close inspection, these lesions have a surface that is "finely verrucous". Most often, these lesions affect the hands or face, and a linear arrangement is not uncommon.

The decision to observe or treat a nevus may depend on a number of factors, including cosmetic concerns, irritative symptoms (e.g., pruritus), ulceration, infection, and concern for potential malignancy.

Experts, such as the American Academy of Dermatology, say that vast majority of moles are benign. Nonetheless, the U.S. National Cancer Institute estimated that 62,480 new cases of melanoma and 8,420 related deaths would appear in the United States in the year 2008.

Data on the chances of transformation from melanocytic nevi to melanoma is controversial, but it appears that about 10% of malignant melanomas have a precursor lesion, of which about 10% are melanocytic nevi. Therefore, it appears that malignant melanoma quite seldomly (1% of cases) has a melanocytic nevi as a precursor.

Pigmented warts are a cutaneous condition commonly reported in Japan, most often occurring on the hands or feet.

Telangiectasia macularis eruptiva perstans is persistent, pigmented, asymptomatic eruption of macules usually less than 0.5 cm in diameter with a slightly reddish-brown tinge.

Melanoacanthoma (also known as "Pigmented seborrheic keratosis") is a common, benign, darkly pigmented cutaneous condition characterized by a skin lesion with a dull or lackluster surface.

It involves a proliferation of keratinocytes and melanocytes.

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.

Smoking or the use of nicotine-containing drugs is the cause to Smoker's melanosis. Also tar-components (benzopyrenes) are known to stimulate melanocytes to melanin production, and other unknown toxic agents in tobacco may also be the cause. These chemical agents have a polycyclic, chain-like structure. Environmental tobacco smoke from parents is causing smoker's melanosis in their children Swedish snuff causes a small elevation of oral melanin pigmented individuals from 3.0% to 4.7%. Nicotine tablets have shown to stimulate to melanin pigmentation of the oral mucosa.

The cause of cutaneous horns is still unknown, but it is believed that exposure to radiation can trigger the condition. This is evidenced by a higher rate of cases occurring on the face and hands, areas that are often exposed to sunlight. Other cases have reported cutaneous horns arising from burn scars. As with many other wart-like skin conditions, a link to the HPV virus family, especially the HPV-2 subtype has been suggested.

A lentigo () (plural lentigines, ) is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign) hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement membrane of the epidermis where melanocytes normally reside. This is in contrast to the "nests" of multi-layer melanocytes found in moles (melanocytic nevi). Because of this characteristic feature, the adjective "lentiginous" is used to describe other skin lesions that similarly proliferate linearly within the basal cell layer.

Lentigines are distinguished from freckles (ephelis) based on the proliferation of melanocytes. Freckles have a relatively normal number of melanocytes but an increased "amount" of melanin. A lentigo has an increased "number" of melanocytes. Freckles will increase in number and darkness with sunlight exposure, whereas lentigines will stay stable in their color regardless of sunlight exposure.

Lentigines by themselves are benign, however one might desire the removal or treatment of some of them for cosmetic purposes. In this case they can be removed surgically, or lightened with the use of topical depigmentation agents. Some common depigmentation agents such as azelaic acid and kojic acid seem to be inefficient in this case, however other agents might work well (4% hydroquinone, 5% topical cysteamine, 10% topical ascorbic acid).

Conditions characterized by lentigines include:

- Lentigo simplex

- Solar lentigo (Liver spots)

- PUVA lentigines

- Ink spot lentigo

- LEOPARD syndrome

- Mucosal lentigines

- Multiple lentigines syndrome

- Moynahan syndrome

- Generalized lentiginosis

- Centrofacial lentiginosis

- Carney complex

- Inherited patterned lentiginosis in black persons

- Partial unilateral lentiginosis

- Peutz-Jeghers syndrome

- Lentigo maligna

- Lentigo maligna melanoma

- Acral lentiginous melanoma

These nevi represent excess growth of blood vessels, including capillaries.

- Nevus simplex (also known as a stork bite, salmon patch, or Nevus flammeus neonatorum)

Large and especially giant congenital nevi are at higher risk for malignancy degeneration into melanoma. Because of the premalignant potential, it is an acceptable clinical practice to remove congenital nevi electively in all patients and relieve the nevocytic overload.

Verruciform xanthoma is uncommon, with a female:male ratio of 1:1.1

Pseudomelanoma (also known as a "recurrent melanocytic nevus", and "recurrent nevus") is a cutaneous condition in which melantic skin lesions clinically resemble a superficial spreading melanoma at the site of a recent shave removal of a melanocytic nevus.

Many other conditions can lead to localized scaling or hyperpigmentation.

This condition should firmly be distinguished from dermatitis artefacta, which is the "factitious" creation of a skin lesion, whereas dermatosis neglecta results from unconscious avoidance of cleaning due to pain or immobility.

Other skin conditions which should not be mistaken for dermatosis neglecta include: terra firma-forme dermatosis (in which there is no history of inadequate cleaning); confluent and reticulated papillomatosis of Gougerot and Carteaud; several forms of ichthyosis; acanthosis nigricans; and Vagabond's disease.

Genital HPV infections have an estimated prevalence in the US of 10–20% and clinical manifestations in 1% of the sexually active adult population. US incidence of HPV infection has increased between 1975 and 2006. About 80% of those infected are between the ages of 17–33. Although treatments can remove the warts, they do not remove the HPV, so warts can recur after treatment (about 50–73% of the time). Warts can also spontaneously regress (with or without treatment).

Traditional theories postulated that the virus remained in the body for a lifetime. However, studies using sensitive DNA techniques have shown that through immunological response the virus can either be cleared or suppressed to levels below what polymerase chain reaction (PCR) tests can measure. One study testing genital skin for subclinical HPV using PCR found a prevalence of 10%.