Odonto–tricho-ungual–digital–palmar syndrome is an autosomal dominant skin condition with salient clinical features of natal teeth, trichodystrophy, prominent interdigital folds, simian-like hands with transverse palmar creases, and ungual digital dystrophy.

Reticulate acropigmentation of Kitamura consists of linear palmar pits and pigmented macules 1 to 4 mm in diameter on the volar and dorsal aspects of the hands and feet, usually inherited in an autosomal-dominant fashion.

Usually, a common form of treatment for the condition is a type of hand cream which moisturises the hard skin. However, currently the condition is incurable.

Pregnancy stretch marks, also known as striae gravidarum, is a specific form of scarring of the skin of the abdominal area due to sudden weight gain during pregnancy. About 90% of women are affected.

A number of additional factors appear to promote the appearance of stretchmarks: one study of 324 women, done just after they had given birth, demonstrated that low maternal age, high body mass index, weight gain over 15 kg (33 pounds) and higher neonatal birth weight were independently correlated with the occurrence of striae. Teenagers were found to be at the highest risk of developing severe striae.

These off-color blemishes are symptoms of pregnancy caused by the tearing of the dermis, resulting in atrophy and loss of rete ridges. These scars often appear as reddish or bluish streaks on the abdomen, and can also appear on the breasts and thighs. Some of these striae disappear with time, while others remain as permanent discolorations of the body.

Mechanical distension and rapidly developing areas of the body during pregnancy (such as the abdomen, breasts, and thighs) are most commonly associated with striae formation. Some have suggested that relaxin and estrogen combined with higher levels of cortisol during pregnancy can cause an accumulation of muocopolysaccharides, which increases water absorption of connective tissue, making it prime for tearing under mechanical stress. There also seems to be an association between higher body mass indices and in women with bigger babies and the incidence and severity of striae. Also, younger women seem to be at higher risk of developing striae during pregnancy.

The prevalence and severity of striae gravidarum varies among populations. The current literature suggest that in the general population of the US, there is a 50%-90% prevalence of striae associated with pregnancy, partly as a result of the normal hormonal changes of pregnancy and partly due to stretching of skin fibers. Many women experience striae gravidarum during their first pregnancy. Nearly 45% percent of women develop striae gravidarum before 24 weeks of gestation. Many women who develop lesions during the first pregnancy do not develop them during later pregnancies. Genetic factors such as family history and race also seem to be predictive in the appearance of striae.

At this time, causes are unknown, but it's said it is not congenital.

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.

ILVEN usually appears in infancy or early childhood. The condition is very rarely begun in adulthood. ILVEN occurs predominantly in females (female-male ratio, 4:1) with no racial predominance.

Trachyonychia, sometimes called sandpapered nails, is a condition characterized by rough accentuated linear ridges (longitudinal striations) on the nails of the fingers and toes. When the condition occurs on all the twenty nails of the fingers and toes, it is known as twenty-nail dystrophy, most evident in childhood, favoring males.

Trachyonychia causes the nails to become opalescent, thin, dull, fragile, and finely longitudinally ridged, and, as a result, distally notched. It can be a manifestation of lichen planus, psoriasis, alopecia areata, immunoglobulin A deficiency, atopic dermatitis, and ichthyosis vulgaris.

"The longitudinal striations can occur as a normal part of the aging process", and not until the nails start to thin and get a sandpaper look is the condition called trachonychia. The nails are opalescent and frequently are brittle and split at the free margin. There has been evidence of the condition as a cutaneous manifestation of lichen planus. It has also been associated with other diseases such as eczema, psoriasis, alopecia areata, and atopic dermatitis. Trachonychia is often seen in vitiligo patients – suggesting that they are more susceptible to this condition.

Lelis syndrome it is a genetic disorder, a rare condition with dermatological and dental findings characterized by the association of ectodermal dysplasia (hypotrichosis and hypohidrosis) with acanthosis nigricans. Other clinical features may include palmoplantar hyperkeratosis, nail dystrophy, intellectual deficit, disturbances of skin pigmentation (perioral and periorbital hyperpigmentation, vitiligo, and perinevic leukoderma) and hypodontia. Transmission is autosomal recessive.

Anetoderma (also known as "Anetoderma maculosa," "Anetoderma maculosa cutis," "Atrophia maculosa cutis," and "Macular atrophy") is a localized laxity of the skin with herniation or outpouching resulting from abnormal dermal elastic tissue. Anetoderma comes in three types:

- "Primary anetoderma"

- Jadassohn–Pellizzari anetoderma is a benign condition with focal loss of dermal elastic tissue. Jadassohn-Pellizzari is one of two major classifications of primary anetoderma, the other being Schweninger–Buzzi anetoderma. The difference between the two is that Jadassohn–Pellizzari anetoderma is preceded by inflammatory lesions.

- Schweninger–Buzzi anetoderma is a cutaneous condition characterized by loss of dermal elastic tissue.

- "Secondary anetoderma"

- "Familial anetoderma"

A systematic review has not found evidence that creams and oils are useful for preventing or reducing stretch marks in pregnancy. The safety in pregnancy of one ingredient, Centella asiatica, has been questioned. Evidence on treatments for reducing the appearance of the scars after pregnancy is limited.

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.

Focal dermal hypoplasia has been associated with PORCN gene mutations on the X chromosome. 90% of the individuals who are affected with the syndrome are female: the commonly accepted, though unconfirmed, explanation for this is that the non-mosaic hemizygous males are not viable.

The differential diagnosis of focal dermal hypoplasia (Goltz) syndrome includes autosomal recessive Setleis syndrome due to TWIST2 gene mutations. It associated with morning glory anomaly, polymicrogyria, incontinentia pigmenti, oculocerebrocutaneous syndrome, Rothmund-Thomson syndrome and microphthalmia with linear skin defects (also known as MLS) syndrome because they are all caused by deletions or point mutations in the HCCS gene.

Palmoplantar keratodermas are a heterogeneous group of disorders characterized by abnormal thickening of the palms and soles.

Autosomal recessive and dominant, X-linked, and acquired forms have all been described.

Reported treatments include topical agents, dermabrasion, cryotherapy, laser therapy, and surgical excision. These therapies have a high failure rate because of incomplete relief of symptoms, scarring, or recurrence .

Though similar in appearance, ILVEN will not respond to therapies known to affect psoriasis. ILVEN can be very difficult to live with but can be treated. The most effective method is full-thickness excision of the lesion. CO2 Laser Surgery can resurface the skin to give a flat, smoother and more normal appearance, but does not remove the lesion.

CVG is classified according to the presence, or lack of underlying cause. Studies suggest that CVG often occurs in individuals in a secondary form to other ailments. However, the condition can also be present on its own. CVG can be classified into two forms: ‘primary’ (essential and non-essential) and ‘secondary’.

The classifications are:

Primary essential CVG is where the cause of the condition in unknown. It has no other associated abnormalities. This occurs mainly in men, with a male:female ratio of 5 or 6:1, and develops during or soon after puberty. Because of the slow progression of the condition, which usually occurs without symptom, it often passes unnoticed in the early stage

Primary non essential CVG can be associated with neuropsychiatric disorders including cerebral palsy, epilepsy, seizures and ophthalmologic abnormalities, most commonly cataracts.

Secondary CVG occurs as a consequence of a number of diseases or drugs that produce changes in scalp structure. These include: acromegaly (excessive growth hormone levels due to pituitary gland tumours), excessive drug use that mimics acromegaly (including the injection of growth hormone itself and drugs that stimulate growth hormone output, such as GHRP-6 and CJC-1295), melanocytic naevi (moles), birthmarks (including connective tissue naevi, fibromas and naevus lipomatosus), and inflammatory processes (e.g., eczema, psoriasis, Darier disease, folliculitis, impetigo, atopic dermatitis, acne).

X-linked reticulate pigmentary disorder (also known as "familial cutaneous amyloidosis", "Partington amyloidosis", "Partington cutaneous amyloidosis", "Partington syndrome type II", "reticulate pigmentary disorder", and "X-linked reticulate pigmentary disorder with systemic manifestations") is a cutaneous condition that has been described in adult women that had linear streaks of hyperpigmentation and in which male patients manifested a reticulated mottled brown pigmentation of the skin, which, on biopsy, demonstrated dermal deposits of amyloid.

The syndrome is also referred with the acronym X-Linked-PDR or even XLPRD.It's a very rare disease, genetically determined, with a chronic course.

It was characterized in 1981. Mutation of the "POLA1" gene leads to loss of expression of the catalytic subunit of DNA polymerase-α and is responsible for XLPDR. Loss of POLA1 expression results in reduced levels of RNA:DNA hybrids in the cytosol and unexpectedly triggers aberrant immune responses (e.g. type I interferon production) which at least in part can account for the symptoms associated with XLPDR.

Congenital malformations of the dermatoglyphs are a cutaneous condition divided into four main categories based on the appearance of the dermal ridges of which they are composed: (1) ridge aplasia; (2) ridge hypoplasia; (3) ridge dissociation; and (4) ridges-off-the-end.

In most cases exfoliation resolves spontaneously and no lasting damage is seen. On the other hand, some patients experience cracking and even bleeding in extreme cases.

Certain hair shampoos and ointments visually thicken existing hair, without affecting the growth cycle. There have also been developments in the fashion industry with wig design. The fashion accessory has also been shown to be a source of psychological support for women undergoing chemotherapy, with cancer survivors in one study describing their wig as a "constant companion". Other studies in women have demonstrated a more mixed psychosocial impact of hairpiece use.

Specialized scalp tattoos can mimic the appearance of a short buzzed haircut.

Phakomatosis pigmentovascularis is a rare neurocutanous condition where there is coexistence of a capillary malformation (port-wine stain) with various melanocytic lesions, including dermal melanocytosis (Mongolian spots), nevus spilus, and nevus of Ota.

Normally, exfoliation is restricted to a particular area and normal skin will replace the exfoliated parts, so no treatment is needed. Since keratolysis exfoliativa is caused by friction, detergents, and solvents, these factors should be avoided. Creams, especially those with silicone and lactic acid are also helpful. In severe cases, photochemotherapy is an option.

Beau's lines are deep grooved lines that run from side to side on the fingernail or the toenail. They may look like indentations or ridges in the nail plate. This condition of the nail was named by a French physician, Joseph Honoré Simon Beau (1806–1865), who first described it in 1846.

Beau's lines are horizontal, going across the nail, and should not be confused with vertical ridges going from the bottom (cuticle) of the nail out to the fingertip. These vertical lines are usually a natural consequence of aging and are harmless. Beau's lines should also be distinguished from Muehrcke's lines of the fingernails. While Beau's lines are actual ridges and indentations in the nail plate, Muehrcke lines are areas of hypopigmentation without palpable ridges; they affect the underlying nail bed, and not the nail itself. Beau's lines should also be distinguished from Mees' lines of the fingernails, which are areas of discoloration in the nail plate.

There are several causes of Beau's lines. It is believed that there is a temporary cessation of cell division in the nail matrix. This may be caused by an infection or problem in the nail fold, where the nail begins to form, or it may be caused by an injury to that area. Some other reasons for these lines include trauma, coronary occlusion, hypocalcaemia, and skin disease. They may be a sign of systemic disease, or may also be caused by an illness of the body, as well as drugs used in chemotherapy or malnutrition. Beau's lines can also be seen one to two months after the onset of fever in children with Kawasaki disease.

Human nails grow at a rate which varies with many factors: age, and the finger or toe in question as well as nutrition. However, typically in healthy populations fingernails grow at about 0.1mm/day and toenails at about 0.05mm/day. With this in mind the date of the stress causing Beau's lines and other identifiable marks on nails can be estimated. As the nail grows out, the ridge visibly moves upwards toward the nail edge. When the ridge reaches the nail edge, the fingertips can become quite sore due to the mis-shapen nail pressing into the flesh deeper than usual, exposing the sensitive nail bed (the quick) at the nail edge.

A researcher found Beau's lines in the fingernails of two of six divers following a deep saturation dive to a pressure equal to 305 meters of sea water, and in six of six divers following a similar dive to 335 meters. They have also been seen in Ötzi the Iceman.

Focal dermal hypoplasia (also known as "Goltz syndrome") is a form of ectodermal dysplasia. It is a multisystem disorder characterized primarily by skin manifestations to the atrophic and hypoplastic areas of skin which are present at birth. These defects manifest as yellow-pink bumps on the skin and pigmentation changes. The disorder is also associated with shortness of stature and some evidence suggests that it can cause epilepsy.

Males are twice as likely as females to have this characteristic, and it tends to run in families. In its non-symptomatic form, it is more common among Asians and Native Americans than among other populations, and in some families there is a tendency to inherit the condition unilaterally, that is, on one hand only.

The presence of a single transverse palmar crease can be, but is not always, a symptom associated with abnormal medical conditions, such as fetal alcohol syndrome, or with genetic chromosomal abnormalities, including Down Syndrome (chromosome 21), cri du chat syndrome (chromosome 5), Klinefelter syndrome, Wolf-Hirschhorn Syndrome, Noonan syndrome (chromosome 12), Patau syndrome (chromosome 13), IDIC 15/Dup15q (chromosome 15), Edward's syndrome (chromosome 18), and Aarskog-Scott syndrome (X-linked recessive), or autosomal recessive disorder, such as Leaukocyte adhesion deficiency-2 (LAD2). A unilateral single palmar crease was also reported in a case of chromosome 9 mutation causing Nevoid basal cell carcinoma syndrome and Robinow syndrome. It is also sometimes found on the hand of the affected side of patients with Poland Syndrome, and craniosynostosis.