Topical fluorouracil (5-FU) destroys AKs by blocking methylation of thymidylate synthetase, thereby interrupting DNA and RNA synthesis. This in turn prevents the proliferation of dysplastic cells in AK. Topical 5-FU is the most utilized treatment for AK, and often results in effective removal of the lesion. Overall, there is a 50% efficacy rate resulting in 100% clearance of AKs treated with topical 5-FU. 5-FU may be up to 90% effective in treating non-hyperkeratotic lesions. The most commonly used application regimen consists of applying a layer of topical cream to the lesion twice a day after washing; duration of treatment is typically 2–4 weeks, but treatment of up to 8 weeks has demonstrated a higher cure rate.

Imiquimod is a topical immune-enhancing agent licensed for the treatment of genital warts. Imiquimod stimulates the immune system through the release and up-regulation of cytokines. Treatment with Imiquimod cream applied 2–3 times per week for 12 to 16 weeks was found to result in complete resolution of AKs in 50% of people, compared to 5% of controls. The Imiquimod 3.75% cream has been validated in a treatment regimen consisting of daily application to entire face and scalp for two 2-week treatment cycles, with a complete clearance rate of 36%. While the clearance rate observed with the Imiquimod 3.75% cream was lower than that observed with the 5% cream (36 and 50 percent, respectively), there are lower reported rates of adverse reactions with the 3.75% cream: 19% of individuals using Imiquimod 3.75% cream reported adverse reactions including local erythema, scabbing, and flaking at the application site, while nearly a third of individuals using the 5% cream reported the same types of reactions with Imiquimod treatment. However, it is ultimately difficult to compare the efficacy of the different strength creams directly, as current study data varies in methodology (e.g. duration and frequency of treatment, and amount of skin surface area covered).

Numerous treatment options are available for photoaged skin, including dermabrasion, topical application of retinoic acid, carbon dioxide laser resurfacing, hyaluronic acid injection into the dermis, imiquimod, tacrolimus ointment, and topical oestrogen therapy. These treatments have variable efficacy.

The most effective prevention strategy for photoaging remains minimization of sun exposure, through use of sunscreen and other sun exposure avoidance measures.

Topical 5-fluorouracil (5-FU, Efudex, Carac) has been shown to be an effective therapy for diffuse, but minor actinic cheilitis. 5-fluorouracil works by blocking DNA synthesis. Cells that are rapidly growing need more DNA, so they accumulate more 5-fluorouracil, resulting in their death. Normal skin is much less affected. The treatment usually takes 2–4 weeks depending on the response. The typical response includes an inflammatory phase, followed by redness, burning, oozing, and finally erosion. Treatment is stopped when ulceration and crusting appear. There is minimal scarring. Complete clearance has been reported in about 50% of patients.

Imiquimod (Aldara) is an immune response modifier that has been studied for the treatment of actinic cheilitis. It promotes an immune response in the skin leading to apoptosis (death) of the tumor cells. It causes the epidermis to be invaded by macrophages, which leads to epidermal erosion. T-cells are also activated as a result of imiquimod treatment. Imiquimod appears to promote an “immune memory” that reduces the recurrence of lesions. There is minimal scarring. Complete clearance has been demonstrated in up to 45% of patients with actinic keratoses. However, the dose and duration of therapy, as well as the long-term efficacy, still need to be established in the treatment of actinic cheilitis.

Currently there is no cure for actinic prurigo, and treatment focuses on relieving the dermatologic symptoms, by way of topical steroid creams or systemic immunosuppressants.

Prescribed treatments include:

- topical creams such as Tacrolimus and Betamethasone.

- systemic immunosuppressants such as Prednisone.

- In some cases, Thalidomide has proven to be effective in controlling the symptoms of actinic prurigo.

All patients with AP are encouraged to minimize sun exposure, and to use strong sunscreen throughout the year, and even on cloudy or overcast days, as UVA light, unlike UVB light, is able to penetrate cloud cover and remains constant throughout the day.

Alternative treatment methods might include UV Hardening, Meditation and/or cognitive behavioral therapy. UV-A desensitization phototherapy has also been shown to be effective in cases.

UV irradiation can be utilized after curetting the hyperkeratosis with a combination medication treatment of oral retinoids, psoralen and Ultraviolet A radiation.

Both cryosurgery and electrosurgery are effective choices for small areas of actinic cheilitis. Cryosurgery is accomplished by applying liquid nitrogen in an open spraying technique. Local anesthesia is not required, but treatment of the entire lip can be quite painful. Cure rates in excess of 96% have been reported. Cryosurgery is the treatment of choice for focal areas of actinic cheilitis. Electrosurgery is an alternate treatment, but local anesthesia is required, making it less practical than cryosurgery. With both techniques, adjacent tissue damage can delay healing and promote scar formation.

More extensive or recurring areas of actinic cheilitis may be treated with either a shave vermillionectomy or a carbon dioxide laser. The shave vemillionectomy removes a portion of the vermillion border but leaves the underlying muscle intact. Considerable bleeding can occur during the procedure due to the vascular nature of the lip. A linear scar may also form after treatment, but this can usually be minimized with massage and steroids. Healing time is short, and effectiveness is very high.

A newer procedure uses a carbon dioxide laser to ablate the vermillion border. This treatment is relatively quick and easy to perform, but it requires a skilled operator. Anesthesia is usually required. Secondary infection and scarring can occur with laser ablation. In most cases, the scar is minimal, and responds well to steroids. Pain can be a progressive problem during the healing phase, which can last three weeks or more. However, the carbon dioxide laser also offers a very high success rate, with very few recurrences.

Chemical peeling with 50% trichloroacetic acid has also been evaluated, but results have been poor. Healing usually takes 7–10 days with very few side effects. However, limited studies show that the success rate may be lower than 30%.

Isotretinoin, high doses of vitamin A and tretinoin cream can be utilized. Also, emollients, oral antihistamines, and antipruritic creams that contain menthol and camphor may be helpful because the lesions can become very itchy.

Surgical removal of the lesion is the first choice of treatment for many clinicians. However, the efficacy of this treatment modality cannot be assessed due to insufficient available evidence. This can be carried out by traditional surgical excision with a scalpel, with lasers, or with eletrocautery or cryotherapy. Often if biopsy demonstrates moderate or severe dysplasia then the decision to excise them is taken more readily. Sometimes white patches are too large to remove completely and instead they are monitored closely. Even if the lesion is completely removed, long term review is still usually indicated since leukoplakia can recur, especially if predisposing factors such as smoking are not stopped.

Many different topical and systemic medications have been studied, including anti-inflammatories, antimycotics (target Candida species), carotenoids (precursors to vitamin A, e.g. beta carotene), retinoids (drugs similar to vitamin A), and cytotoxics, but none have evidence that they prevent malignant transformation in an area of leukoplakia.Vitamins C and E have also been studied with regards a therapy for leukoplakia. Some of this research is carried out based upon the hypothesis that antioxidant nutrients, vitamins and cell growth suppressor proteins (e.g. p53) are antagonistic to oncogenesis. High doses of retinoids may cause toxic effects. Other treatments that have been studied include photodynamic therapy.

Actinic granuloma (also known as "O'Brien granuloma") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

Actinic granuloma is an asymptomatic granulomatous reaction that affects sun-exposed skin, most commonly on the face, neck, and scalp.

It is characterized by annular or polycyclic lesions that slowly expand centrifugally and have an erythematous elevated edge and a hypopigmented, atrophic center.

Advise to reduce exposure to the sun and to use sunscreen.

Treatment with topical halometasone cream, pimecrolimus cream.

Corns and calluses are easier to prevent than to treat. When it is usually not desirable to form a callus, minimizing rubbing and pressure will prevent callus formation. Footwear should be properly fitted, gloves may be worn, and protective pads, rings or skin dressings may be used. People with poor circulation or sensation should check their skin often for signs of rubbing and irritation so they can minimize any damage.

Topical corticosteroid preparations are the most effective agents when used continuously for 8 weeks; retinoids and coal tar were found to be of limited benefit and may be no better than placebo. Greater benefit has been observed with very potent corticosteroids when compared to potent corticosteroids. Vitamin D analogues such as paricalcitol were found to be significantly superior to placebo. Combination therapy with vitamin D and a corticosteroid was superior to either treatment alone and vitamin D was found to be superior to coal tar for chronic plaque psoriasis.

Moisturizers and emollients such as mineral oil, petroleum jelly, calcipotriol, and decubal (an oil-in-water emollient) were found to increase the clearance of psoriatic plaques. Emollients have been shown to be even more effective at clearing psoriatic plaques when combined with phototherapy. However, certain emollients have no impact on psoriasis plaque clearance or may even decrease the clearance achieved with phototherapy. The emollient salicylic acid is structurally similar to para-aminobenzoic acid (PABA), commonly found in sunscreen, and is known to interfere with phototherapy in psoriasis. Coconut oil, when used as an emollient in psoriasis, has been found to decrease plaque clearance with phototherapy. Medicated creams and ointments applied directly to psoriatic plaques can help reduce inflammation, remove built-up scale, reduce skin turnover, and clear affected skin of plaques. Ointment and creams containing coal tar, dithranol, corticosteroids (i.e. desoximetasone), fluocinonide, vitamin D analogs (for example, calcipotriol), and retinoids are routinely used. The use of the finger tip unit may be helpful in guiding how much topical treatment to use.

Vitamin D analogues may be useful with steroids; however, alone have a higher rate of side effects. They may allow less steroids to be used.

Another topical therapy used to treat psoriasis is a form of balneotherapy, which involves daily baths in the Dead Sea. This is usually done for four weeks with the benefit attributed to sun exposure and specifically UVB light. This is cost-effective and it has been propagated as an effective way to treat psoriasis without medication. Decreases of PASI scores greater than 75% and remission for several months have commonly been observed. Side-effects may be mild such as itchiness, folliculitis, sunburn, poikiloderma, and a theoretical risk of nonmelanoma skin cancer or melanoma has been suggested. However, more recent studies have determined that there does not appear to be increased risk of melanoma in the long-term. Data are inconclusive with respect to nonmelanoma skin cancer risk, but support the idea that the therapy is associated with an increased risk of benign forms of sun-induced skin damage such as, but not limited to, actinic elastosis or liver spots. Dead Sea balneotherapy is also effective for psoriatic arthritis.

Calluses and corns may go away by themselves eventually, once the irritation is consistently avoided. They may also be dissolved with keratolytic agents containing salicylic acid, sanded down with a pumice stone or silicon carbide sandpaper or filed down with a callus shaver, or pared down by a professional such as a podiatrist or a foot health practitioner.

Immunotherapy research suggests that treatment using "Euphorbia peplus", a common garden weed, may be effective. Australian biopharmaceutical company Peplin is developing this as topical treatment for BCC. Imiquimod is an immunotherapy but is listed here under chemotherapy.

Pterygium typically do not require surgery unless it grows to such an extent that it causes visual problems. Some of the symptoms such as irritation can be addressed with artificial tears. Surgery may also be considered for unmanageable symptoms.

Phototherapy in the form of sunlight has long been used for psoriasis. Wavelengths of 311–313 nanometers are most effective, and special lamps have been developed for this application. The exposure time should be controlled to avoid over exposure and burning of the skin. The UVB lamps should have a timer that will turn off the lamp when the time ends. The amount of light used is determined by a person's skin type. Increased rates of cancer from treatment appear to be small. Narrow band UVB light (NBUVB) phototherapy has been demonstrated to have similar efficacy to PUVA.

One of the problems with clinical phototherapy is the difficulty many patients have gaining access to a facility. Indoor tanning resources are almost ubiquitous today and could be considered as a means for patients to get UV exposure when dermatologist provided phototherapy is not available. Indoor tanning is already used by many people as a treatment for psoriasis; one indoor facility reported that 50% of its clients were using the center for psoriasis treatment; another reported 36% were doing the same thing. However, a concern with the use of commercial tanning is that tanning beds that primarily emit UVA might not effectively treat psoriasis. One study found that plaque psoriasis is responsive to erythemogenic doses of either UVA or UVB, as exposure to either can cause dissipation of psoriatic plaques. It does require more energy to reach erythemogenic dosing with UVA.

UV light therapies all have risks; tanning beds are no exception, particularly in the link between UV light and the increased chance of skin cancer. There are increased risks of melanoma, squamous cell and basal cell carcinomas; younger psoriasis patients, particularly those under age 35, are at increased risk from melanoma from UV light treatment. The World Health Organization (WHO) listed tanning beds as carcinogens. A review of studies recommends that people who are susceptible to skin cancers exercise caution when using UV light therapy as a treatment.

A major mechanism of NBUVB is the induction of DNA damage in the form of pyrimidine dimers. This type of phototherapy is useful in the treatment of psoriasis because the formation of these dimers interferes with the cell cycle and stops it. The interruption of the cell cycle induced by NBUVB opposes the characteristic rapid division of skin cells seen in psoriasis. The activity of many types of immune cells found in the skin is also effectively suppressed by NBUVB phototherapy treatments. The most common short-term side effect of this form of phototherapy is redness of the skin; less common side effects of NBUVB phototherapy are itching and blistering of the treated skin, irritation of the eyes in the form of conjunctival inflammation or inflammation of the cornea, or cold sores due to reactivation of the herpes simplex virus in the skin surrounding the lips. Eye protection is usually given during phototherapy treatments.

Psoralen and ultraviolet A phototherapy (PUVA) combines the oral or topical administration of psoralen with exposure to ultraviolet A (UVA) light. The mechanism of action of PUVA is unknown, but probably involves activation of psoralen by UVA light, which inhibits the abnormally rapid production of the cells in psoriatic skin. There are multiple mechanisms of action associated with PUVA, including effects on the skin's immune system. PUVA is associated with nausea, headache, fatigue, burning, and itching. Long-term treatment is associated with squamous cell carcinoma (but not with melanoma). A combination therapy for moderate to severe psoriasis using PUVA plus acitretin resulted in benefit, but acitretin use has been associated with birth defects and liver damage.

Appropriate sun-protective clothing, use of broad-spectrum (UVA/UVB) sunscreen with at least SPF 50, and avoidance of intense sun exposure may prevent skin cancer.

A Cochrane review found conjunctival autograft surgery was less likely to have reoccurrence of the pterygium at 6 months compared to amniotic membrane transplant. More research is needed to determine which type of surgery resulted in better vision or quality of life. The additional use of mitomycin C is of unclear effect. Radiotherapy has also be used in an attempt to reduce the risk of recurrence.

Some superficial cancers respond to local therapy with 5-fluorouracil, a chemotherapy agent. Topical treatment with 5% Imiquimod cream, with five applications per week for six weeks has a reported 70–90% success rate at reducing, even removing, the BCC [basal-cell carcinoma]. Both Imiquimod and 5-fluorouracil have received FDA approval, and topical IMQ is approved by the European Medicines Agency for treatment of small superficial basal-cell carcinoma. Off label use of imiquimod on invasive basal-cell carcinoma has been reported. Imiquimod may be used prior to surgery in order to reduce the size of the carcinoma. One can expect a great deal of inflammation with this treatment. Chemotherapy often follows Mohs surgery to eliminate the residual superficial basal-cell carcinoma after the invasive portion is removed. Some advocate the use of imiquimod prior to Mohs surgery to remove the superficial component of the cancer. Removing the residual superficial tumor with surgery alone can result in large and difficult to repair surgical defects. One often waits a month or more after surgery before starting the Imiquimod or 5-fluorouracil to make sure the surgical wound has adequately healed. Some people advocate the use of curettage (see EDC below) first, followed by chemotherapy. These experimental procedures are not standard care. The 2008 study reported that topical IMQ appears effective in the treatment of primary small superficial BCCs, but only 'may possibly' have a role in the treatment of primary nodular BCC.

Approved in 2012, vismodegib is used to treat an advanced form of basal-cell carcinoma.

Actinic elastosis, also known as solar elastosis, is an accumulation of abnormal elastin (elastic tissue) in the dermis of the skin, or in the conjunctiva of the eye, which occurs as a result of the cumulative effects of prolonged and excessive sun exposure, a process known as photoaging.

Most squamous cell carcinomas are removed with surgery. A few selected cases are treated with topical medication. Surgical excision with a free margin of healthy tissue is a frequent treatment modality. Radiotherapy, given as external beam radiotherapy or as brachytherapy (internal radiotherapy), can also be used to treat squamous cell carcinomas.

Mohs surgery is frequently utilized; considered the treatment of choice for squamous cell carcinoma of the skin, physicians have also utilized the method for the treatment of squamous cell carcinoma of the mouth, throat, and neck. An equivalent method of the CCPDMA standards can be utilized by a pathologist in the absence of a Mohs-trained physician. Radiation therapy is often used afterward in high risk cancer or patient types.

Electrodessication and curettage or EDC can be done on selected squamous cell carcinoma of the skin. In areas where SCC's are known to be non-aggressive, and where the patient is not immunosuppressed, EDC can be performed with good to adequate cure rate.

High-risk squamous cell carcinoma, as defined by those occurring around the eye, ear, or nose, is of large size, is poorly differentiated, and grows rapidly, requires more aggressive, multidisciplinary management.

Nodal spread:

1. Surgical block dissection if palpable nodes or in cases of Marjolin's ulcers but the benefit of prophylactic block lymph node dissection with Marjolin's ulcers is not proven.

2. Radiotherapy

3. Adjuvant therapy may be considered in those with high-risk SCC even in the absence of evidence for local mestastasis. Imiquimod (Aldara) has been used with success for squamous cell carcinoma "in situ" of the skin and the penis, but the morbidity and discomfort of the treatment is severe. An advantage is the cosmetic result: after treatment, the skin resembles normal skin without the usual scarring and morbidity associated with standard excision. Imiquimod is not FDA-approved for any squamous cell carcinoma.

In general, squamous cell carcinomas have a high risk of local recurrence, and up to 50% do recur. Frequent skin exams with a dermatologist is recommended after treatment.

Solar purpura (also known as "Actinic purpura," and "Senile purpura") is a skin condition characterized by large, sharply outlined, 1- to 5-cm, dark purplish-red ecchymoses appearing on the dorsa of the forearms and less often the hands.

The condition is most common in elderly people of European descent. It is caused by sun-induced damage to the connective tissue of the skin.

No treatment is necessary. The lesions typically fade over a period of up to 3 weeks.

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.

Porokeratosis is a specific disorder of keratinization that is characterized histologically by the presence of a cornoid lamella, a thin column of closely stacked, parakeratotic cells extending through the stratum corneum with a thin or absent granular layer.