PVA can be characterized by speckled, combined hyper- and hypopigmentation in the plaques or patches of affected skin. Hyperpigmentation is excess coloration, or darkening of the skin, while hypopigmentation is a diminished or pallid coloring to the skin. Pigmentation changes in PVA, apparent in the epidermal (outermost) skin layer, may be attributed to incontinence (leaking out) of melanin from melanocytes into the dermal skin layer below. Inflammation of the skin and cutaneous tissue, common with PVA, also contributes to color changes in the skin, typified by redness. Telangiectasia, the visible "vascular" element of PVA, is the of small blood vessels near the skin surface. Skin atrophy, a wasting-away of the tissue comprising the skin, is a prominent part of PVA and effects the dermal, and particularly the epidermal layer. This, in part, is the result of degenerative of the stratum basale (bottom cell-layer) of the epidermis. Atrophy of the skin gives it a thin, dry and wrinkled appearance, which in PVA-affected individuals has been described as "cigarette paper". Hyperkeratosis, a thickening of the stratum corneum (top cell-layer of the epidermis), has also been reported.

Sufferers experience very fragile skin, with blisters and skin erosion occurring in response to relatively benign trauma. Blisters may form all over the body, including the mucous membranes. Chronic scarring can lead to the formation of granulation tissue, which may bleed easily, predisposing to infection. Hands and fingers may be affected, as well as various joints.

Junctional epidermolysis bullosa is a skin condition characterized by blister formation within the lamina lucida of the basement membrane zone.

Although lichen planus can present with a variety of lesions, the most common presentation is as a well defined area of purple-coloured, itchy, flat-topped papules with interspersed lacy white lines (Wickham's striae). This description is known as the characteristic "6 Ps" of lichen planus: planar (flat-topped), purple, polygonal, pruritic, papules, and plaques. This rash, after regressing, is likely to leave an area of hyperpigmentation that slowly fades. That said, a variety of other lesions can also occur.

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.

PVA usually has an underlying cause, attributed to existing skin diseases and disorders associated with a cutaneous lymphoma or inflammation. Mycosis fungoides is the common lymphoma believed to cause PVA, although it may be considered a precursor when the lymphoma is (hidden) and undiagnosed. Large plaque parapsoriasis is another common causes of PVA. Less common causes include autoimmune-related connective tissue diseases such as lupus, dermatomyositis and scleroderma. Dermatoses and those that are genetically inspired, called genodermatoses, may also be an underlying cause of PVA. Among them, xeroderma pigmentosum and Rothmund-Thomson syndrome (poikiloderma congenita) are thought to be the most prominent. Ingestion of substances containing arsenic, such as arsphenamine, has also been suggested as a least common cause. PVA can also be idiopathic (of unknown cause), as seen in a small number of cases.

Variants of cutaneous lichen planus are distinguished based upon the appearance of the lesions and/or their distribution. Lesions can affect the:

- Extremities (face, dorsal hands, arms, and nape of neck). This is more common in Middle Eastern countries in spring and summer, where sunlight appears to have a precipitating effect.

- Palms and soles

- Intertriginous areas of the skin. This is also known as "Inverse lichen planus."

- Nails characterized by irregular longitudinal grooving and ridging of the nail plate, thinning of the nail plate, pterygium formation, shedding of the nail plate with atrophy of the nail bed, subungual keratosis, longitudinal erthronychia (red streaks), and subungual hyperpigmentation. A sand-papered appearance is present in around 10% of individuals with nail lichen planus.

- Hair and Scalp. The scalp is rarely affected by a condition known as lichen planopilaris, acuminatus, follicular lichen planus, and peripilaris, characterised by violaceous, adherent follicular scale with progressive scarring alopecia. While lichen planus and lichen planopilaris may occur together, aside from sharing the term ‘lichen’ and revealing inflammation on skin biopsy, there is neither established data on their co-occurrence nor data to suggest a common etiology. Lichen planopilaris is considered an orphan disease with no definitive prevalence data and no proven effective treatments.

Other variants may include:

- "Lichen planus pemphigoides" characterized by the development of tense blisters atop lesions of lichen planus or the development vesicles de novo on uninvolved skin.

- "Keratosis lichenoides chronica" (also known as "Nekam's disease") is a rare dermatosis characterized by violaceous papular and nodular lesions, often arranged in a linear or reticulate pattern on the dorsal hands and feet, extremities, and buttock, and some cases manifest by sorrheic dermatitis-like eruption on the scalp and face; also palmo plantar keratosis has been reported.

- "Lichenoid keratoses" (also known as "Benign lichenoid keratosis," and "Solitary lichen planus") is a cutaneous condition characterized by brown to red scaling maculopapules, found on sun-exposed skin of extremities. Restated, this is a cutaneous condition usually characterized by a solitary dusky-red to violaceous papular skin lesion.

- "Lichenoid dermatitis" represents a wide range of cutaneous disorders characterized by lichen planus-like skin lesions.

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.

Actinic keratoses ("AKs") most commonly present as a white, scaly plaque of variable thickness with surrounding redness; they are most notable for having a sandpaper-like texture when felt with a gloved hand. Skin nearby the lesion often shows evidence of solar damage characterized by notable pigmentary alterations, being yellow or pale in color with areas of hyperpigmentation; deep wrinkles, coarse texture, purpura and ecchymoses, dry skin, and scattered telangiectasias are also characteristic. Photoaging leads to an accumulation of oncogenic changes, resulting in a proliferation of mutated keratinocytes that can manifest as AKs or other neoplastic growths. With years of sun damage, it is possible to develop multiple AKs in a single area on the skin.

The lesions are usually asymptomatic, but can be tender, itch, bleed, or produce a stinging or burning sensation. AKs are typically graded in accordance with their clinical presentation: Grade I (easily visible, slightly palpable), Grade II (easily visible, palpable), and Grade III (frankly visible and hyperkeratotic).

The cause is unknown but is thought to be associated with diabetic neuropathy and vascular complications; because the lesions are more common on the shins, some suggest it represents an altered response to injury. It is seen more commonly in patients with longstanding diabetes and poor glucose control.

Actinic keratoses can have various clinical presentations, often characterized as follows:

- Classic (or common): Classic AKs present as white, scaly macules, papules or plaques of various thickness, often with surrounding erythema. They are usually 2-6mm in diameter but can sometimes reach several centimeters in diameter.

- Hypertrophic (or hyperkeratotic): Hypertrophic AKs (HAKs) appear as a thicker scale or rough papule or plaque, often adherent to an erythematous base. Classic AKs can progress to become HAKs, and HAKs themselves can be difficult to distinguish from malignant lesions.

- Atrophic: Atrophic AKs lack an overlying scale, and therefore appear as a nonpalpable change in color (or macule). They are often smooth and red, and are less than 10mm in diameter.

- AK with cutaneous horn: A cutaneous horn is a keratinic projection with its height at least one-half of its diameter, often conical in shape. They can be seen in the setting of actinic keratosis as a progression of an HAK, but are also present in other skin conditions. 38–40% of cutaneous horns represent AKs.

- Pigmented AK: Pigmented AKs are rare variants that often present as macules or plaques that are tan to brown in color. They can be difficult to distinguish from a solar lentigo or lentigo maligna.

- Actinic cheilitis: When an AK forms on the lip, it is called actinic cheilitis. This usually presents as a rough, scaly patch on the lip, often accompanied by the sensation of dry mouth and symptomatic splitting of the lips.

- Bowenoid AK: Usually presents as a solitary, erythematous, scaly patch or plaque with well-defined borders. Bowenoid AKs are differentiated from Bowen's disease by degree of epithelial involvement as seen on histology.

The presence of ulceration, nodularity, or bleeding should raise concern for malignancy. Specifically, clinical findings suggesting an increased risk of progression to squamous cell carcinoma can be recognized as "IDRBEU": I (induration /inflammation), D (diameter > 1 cm), R (rapid enlargement), B (bleeding), E (erythema) and U (ulceration). AKs are usually diagnosed clinically, but because they are difficult to clinically differentiate from squamous cell carcinoma, any concerning features warrant biopsy for diagnostic confirmation.

CGPD is known to be a temporary skin disease with a benign course. The skin papules typically resolve after a few months to a few years. After CGPD resolves, the skin may return to normal without scarring or may have small atrophic depressions with collagen loss, milia, or small pit-like scars.

Diabetic dermopathy (also known as "shin spots") is a type of skin lesion usually seen in people with diabetes mellitus. It is characterized by dull-red papules that progress to well-circumscribed, small, round, atrophic hyperpigmented skin lesions usually on the shins. It is the most common of several diabetic skin conditions, being found in up to 30% of diabetics. Similar lesions can occasionally be found in non-diabetics usually following trauma or injury to the area; however, >4 lesions strongly suggests diabetes.

CGPD is characterized by the presence of small, raise, dome-shape papules primarily distributed around the mouth, eyes, and nose. Affected children may also have papules on the ears, eyelids, cheeks, forehead, and nose. CGPD skin lesions affecting areas of the skin other than the face are rare.

Rombo syndrome is a very rare genetic disorder characterized mainly by atrophoderma vermiculatum of the face, multiple milia, telangiectases, acral erythema, peripheral vasodilation with cyanosis and a propensity to develop basal cell carcinomas.

The lesions become visible in late childhood, began at ages 7 to 10 years and are most pronounced on the face, At that time a pronounced, somewhat cyanotic redness of the lips and hands was evident as well as moderate follicular atrophy of the skin on the cheeks. In adulthood, whitish-yellow, milia-like papules and telangiectatic vessels developed. The papules were present particularly on the cheeks and forehead, gradually becoming very conspicuous and dominating the clinical picture. Trichoepitheliomas were found in 1 case. In adults, the eyelashes and eyebrows were either missing or irregularly distributed with defective and maldirected growth. Basal cell carcinomas were a frequent complication. The skin atrophy was referred to as vermiculate atrophoderma. Basal cell carcinomas may develop around the age of 35. Histological observations during the early stage include irregularly distributed and atrophic hair follicles, milia, dilated dermal vessels, lack of elastin or elastin in clumps. After light irradiation a tendency to increased repair activity was observed both in epidermis and in the dermal fibroblasts.

Histologic sections showed the dermis to be almost devoid of elastin in most areas with clumping of elastic material in other areas. The disorder had been transmitted through at least 4 generations with instances of male-to-male transmission.

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.

Linear focal elastosis (also known as "Elastotic striae") presents with asymptomatic, palpable or atrophic, yellow lines of the middle and lower back, thighs, arms and breasts.

The characteristic symptom of Degos disease is the development of papules. Initially, individuals may have skin lesions or rashes, but they will proceed to develop distinct bumps, or papules. Papules are circular in shape, have a porcelain-white center and red border. As papules age, the white centers will skin in and only the border will remain raised. Typically, papules range from 0.5 to 1 cm in width. Papules appear on the trunk and upper extremities and are not found on the individual's palms, soles, scalp, or face.

Depending on whether an individual has the benign variant or malignant variant of the disease symptoms will vary. Both the benign and malignant forms have development of the characteristic papules. Individuals with the benign form will have the typical papules persisting anywhere from a few years to throughout their whole lives. In the benign form, no inner organs are affected. If an individual develops the malignant form, it means that not only are the papules present, but inner organs are involved. Most malignant cases involve problems of the gastrointestinal tract leading to small intestine lesions, abdominal pain, diarrhea, and bowel perforation. If the central nervous system is involved, symptoms can include headaches, dizziness, seizures, paralysis of cranial nerves, weakness, stroke, damage to small areas of the brain due to artery blockage (cerebral infarcts, and cerebral hemorrhage). Additional organs commonly impacted include the heart, lungs, and kidneys. Symptoms that may develop from damage to these organs include double vision (diploplia), clouding of lenses of eyes, swelling of the optic disc (papilledema), partial loss of vision, shortness of breath, chest pain, epilepsy,and thickening of pericardium.

Someone with the benign form may suddenly develop symptoms of the malignant form. Symptoms can last anywhere from a few weeks to several years. Onset of symptoms typically begins to manifest between the ages of 20-50. A few cases of this condition in newborns have also been described.

Erythema ab igne (EAI, also known as hot water bottle rash, fire stains, laptop thigh, granny's tartan and toasted skin syndrome) is a skin condition caused by long-term exposure to heat (infrared radiation). Prolonged thermal radiation exposure to the skin can lead to the development of reticulated erythema, hyperpigmentation, scaling and telangiectasias in the affected area. Some people may complain of mild itchiness and a burning sensation, but often, unless a change in pigmentation is seen, it can go unnoticed.

Terminal osseous dysplasia with pigmentary defects is a cutaneous condition characterized by hyperpigmented, atrophic facial macules.

It has been associated with "FLNA".

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.

Atrophic connective tissue panniculitis is a rare condition, and often occurs on the upper or lower extremities.

Acne conglobata presents with blackheads appearing around the face, neck, chest, upper arms and buttocks in groups of two or three. Pimples form around the blackheads; they are large and engorged with fluid and may be sensitive to touch. They remain for a while and continue to grow and fill with pus until they eventually rupture. After the lesion has drained, it fills up again. After they rupture, several nodules can fuse together to form larger shapes. The lesions remain for a long time. They form a scab in the center but they continue to spread outwards. When the lesions do eventually heal, they leave scars that can be the usual type of acne scar (atrophic) or a raised bump like those normally left behind by a burn or a cut (keloidal).

Different types of heat sources can cause this condition such as:

- Repeated application of hot water bottles, heating blankets or heat pads to treat chronic pain—e.g., chronic backache.

- Repeated exposure to heated car seats, space heaters, or fireplaces. Repeated or prolonged exposure to a heater is a common cause of this condition in elderly individuals.

- Occupational hazards of silversmiths and jewellers (face exposed to heat), bakers and chefs (arms)

- Resting a laptop computer on the thigh (laptop computer-induced erythema ab igne). In a 2012 review, Riahi and Cohen describe the characteristics of laptop computer-induced erythema ab igne. Temperatures between 43-47 °C can cause this skin condition; modern laptops can generate temperatures in this range. Indeed, laptops with powerful processors can reach temperatures of 50 °C and be associated with burns. Positioning of the laptop on the thighs can allow for direct exposure to the heating elements of the laptop, which include the central processing unit (CPU) and the graphics processing unit (GPU). At least 15 cases have been reported by 2012 with the condition usually affecting the left anterior thigh. In these reports, 9 of the 15 patients were women (60%) with an average age of 25 years at diagnosis.

- In Kashmir, due to the use of a kanger which also causes kangri cancer

- It is a classic finding in chronic pancreatitis and may also be seen in people with hypothyroidism or lymphoedema

Geographic tongue could be considered to be a type of glossitis. It usually presents only on the dorsal 2/3 and lateral surfaces of the tongue, but less commonly an identical condition can occur on other mucosal sites in the mouth, such as the ventral surface (undersurface) of the tongue, mucosa of the cheeks or lips, soft palate or floor of mouth; usually in addition to tongue involvement. In such cases, terms such as stomatitis erythema migrans, ectopic geographic tongue, areata migrans, geographic stomatitis, or migratory stomatitis are used instead of geographic tongue. Beside the differences in locations of presentation inside the oral cavity and prevalence among the general population, in all other aspects of clinical significance, symptoms, treatment, and histopathologic appearance, these two forms are identical.

This condition is sometimes termed (oral) erythema migrans, but this has no relation to the more common use of the term erythema migrans (erythema chronicum migrans), to describe the appearance of skin lesions in Lyme disease.