Clinically, three distinct patterns of palmoplantar keratoderma may be identified: diffuse, focal, and punctate.

Diffuse palmoplantar keratoderma is a type of palmoplantar keratoderma that is characterized by an even, thick, symmetric hyperkeratosis over the whole of the palm and sole, usually evident at birth or in the first few months of life. Restated, diffuse palmoplantar keratoderma is an autosomal dominant disorder in which hyperkeratosis is confined to the palms and soles. The two major types can have a similar clinical appearance:

- "Diffuse epidermolytic palmoplantar keratoderma" (also known as "Palmoplantar keratoderma cum degeneratione granulosa Vörner," "Vörner's epidermolytic palmoplantar keratoderma", and "Vörner keratoderma") is one of the most common patterns of palmoplantar keratoderma, an autosomal dominant condition that presents within the first few months of life, characterized by a well-demarcated, symmetric thickening of palms and soles, often with a "dirty" snakeskin appearance due to underlying epidermolysis.

- "Diffuse nonepidermolytic palmoplantar keratoderma" (also known as "Diffuse orthohyperkeratotic keratoderma," "Hereditary palmoplantar keratoderma," "Keratosis extremitatum progrediens," "Keratosis palmoplantaris diffusa circumscripta," "Tylosis," "Unna–Thost disease", and "Unna–Thost keratoderma") is inherited as an autosomal dominant condition and is present from infancy, characterized by a well-demarcated, symmetric, often "waxy" keratoderma involving the whole of the palms and soles.

Hidrotic ectodermal dysplasia 2, or Clouston syndrome (referred to as HED2 throughout this entry) is characterized by partial or total alopecia, dystrophy of the nails, hyperpigmentation of the skin (especially over the joints), and clubbing of the fingers. Sparse scalp hair and dysplastic nails are seen early in life. In infancy, scalp hair is wiry, brittle, patchy, and pale; progressive hair loss may lead to total alopecia by puberty. The nails may be milky white in early childhood; they gradually become dystrophic, thick, and distally separated from the nail bed. Palmoplantar keratoderma may develop during childhood and increases in severity with age. The clinical manifestations are highly variable even within the same family.

IBS has symptoms very similar to epidermolytic hyperkeratosis (EHK) but is generally milder than EHK. IBS affects only the upper layers of the epidermis whilst EHK affects the suprabasal layer which is deeper in the

skin.

At birth the baby's skin has a red appearance like a sun burn (erythema). Blistering is usually present at birth and may be extensive or localized depending on the severity of the disease.

Over the first few weeks the redness disappears and is replaced by dry, flaking skin on the arms, legs and around the belly button. Other areas of skin appear normal. The skin is fragile and is prone to blistering (caused by mild trauma or sweating). After a few months hyperkeratosis develops with a dark grey or brown, ridged appearance on the ankles, knees and elbows. Palms and soles are generally unaffected. A slightly unpleasant, sweet odour may be present.

A distinctive characteristic of IBS which is not present in other forms of ichthyosis is called the "Mauserung phenomenon" (Mauserung is German for "moulting" and was first described by H.W.Siemens). These are small patches of bare, apparently normal skin in the middle of areas of hyperkeratosis.

As the sufferer ages the flaking and blistering should improve. The hyperkeratosis may grow more severe but more localized and is generally only present on flexural folds of the major joints.

Epidermolytic hyperkeratosis is a skin disorder that is present at birth. Affected babies may have very red skin (erythroderma) and severe blisters. Because newborns with this disorder are missing the protection provided by normal skin, they are at risk of becoming dehydrated and developing infections in the skin or throughout the body (sepsis).

As affected individuals get older, blistering is less frequent, erythroderma becomes less evident, and the skin becomes thick (hyperkeratotic), especially over joints, on areas of skin that come into contact with each other, or on the scalp or neck. This thickened skin is usually darker than normal. Bacteria can grow in the thick skin, often causing a distinct odor.

Epidermolytic hyperkeratosis can be categorized into two types. People with PS-type epidermolytic hyperkeratosis have thick skin on the palms of their hands and soles of their feet (palmoplantar or palm/sole hyperkeratosis) in addition to other areas of the body. People with the other type, NPS-type, do not have extensive palmoplantar hyperkeratosis but do have hyperkeratosis on other areas of the body.

Epidermolytic hyperkeratosis is part of a group of conditions called ichthyoses, which refers to the scaly skin seen in individuals with related disorders. However, in epidermolytic hyperkeratosis, the skin is thick but not scaly as in some of the other conditions in the group.

"http://ghr.nlm.nih.gov/condition/epidermolytic-hyperkeratosis"

The symptoms of ichthyosis hystrix Curth-Macklin are similar to epidermolytic hyperkeratosis (NPS-2 type) but there is no blistering and the hyperkeratosis is verrucous or spine-like. The hyperkeratosis is brown-grey in colour and is most obvious on the arms and legs. It is an autosomal dominant condition and can be caused by errors to the KRT1 gene. It is named after Helen Ollendorff Curth (1899-1982), a German-Jewish dermatologist, and Madge Thurlow Macklin (1893–1962), an American medical geneticist, and is one of the first syndromes named after two women.

CIE has symptoms very similar to Lamellar ichthyosis (LI) but milder and is considered by many scientists to be a variant of that disease, so both diseases are grouped under the title autosomal recessive congenital ichthyosis (ARCI).

The baby is often born in a collodion membrane, a shiny, wax outer layer on the skin and usually with ectropion, having the lower eyelid turned outwards. When the membrane is shed the skin is red with a generalized white scale. Palms, soles and areas on the joints are often affected with hyperkeratosis, a thickening of the layer of dead skin cells on the surface of the skin. In classical CIE (unlike LI) there is little eclabion (eversion of the lips), ectropion and alopecia (hair loss).

Many people with ACRI don't fit neatly into the definition of LI or CIE but have characteristics of both diseases. The definitions of CIE and LI describe the extremes of the range of ACRI.

Ichthyosis hystrix is a group of rare skin disorders in the ichthyosis family of skin disorders characterized by massive hyperkeratosis with an appearance like spiny scales. This term is also used to refer to a type of epidermal nevi with extensive bilateral distribution.

Ichthyosis bullosa of Siemens is a type of familial, autosomal dominant ichthyosis, a rare skin disorder. It is also known as bullous congenital ichthyosiform erythroderma of Siemens or ichthyosis exfoliativa. It is a genetic disorder with no known cure which is estimated to affect about 1 in 500,000 people.

Acrokeratosis verruciformis (also known as "Acrokeratosis verruciformis of Hopf" is a rare autosomal dominant disorder appearing at birth or in early childhood, characterized by skin lesions that are small, verrucous, flat papules resembling warts along with palmoplantar punctate keratoses and pits. However sporadic forms, whose less than 10 cases have been reported, presents at a later age, usually after the first decade and generally lack palmoplantar keratoses.

Whether acrokeratosis verruciformis and Darier disease are related or distinct entities has been controversial, like Darier's disease, it is associated with defects in the ATP2A2 gene. however the specific mutations found in the ATP2A2 gene in acrokeratosis verruciformis have never been found in Darier's disease.

The presentation may be of alopecia (baldness). Individuals vary in severity of symptoms. Nail deformities may also be present as well as hair follicle keratosis and follicular hyperkeratosis.

In medicine, the term collodion baby applies to newborns who appear to have an extra layer of skin (known as a "collodion membrane") that has a collodion-like quality. It is a descriptive term, not a specific diagnosis or disorder (as such, it is a syndrome).

HED2 is suspected after infancy on the basis of physical features in most affected individuals. GJB6 is the only gene known to be associated with HED2. Targeted mutation analysis for the four most common GJB6 mutations is available on a clinical basis and detects mutations in approximately 100% of affected individuals. Sequence analysis is also available on a clinical basis for those in whom none of the four known mutations is identified.

Affected babies are born in a collodion membrane, a shiny, waxy-appearing outer layer to the skin. This is shed 10–14 days after birth, revealing the main symptom of the disease, extensive scaling of the skin caused by hyperkeratosis.

With increasing age, the scaling tends to be concentrated around joints in areas such as the groin, the armpits, the inside of the elbow and the neck. The scales often tile the skin and may resemble fish scales.

Epidermolytic ichthyosis (EI), (also known as "epidermolytic hyperkeratosis (EHK)", "bullous congenital ichthyosiform erythroderma (BCIE), bullous ichthyosiform erythroderma, or bullous congenital ichthyosiform erythroderma Brocq) is a rare and severe form of ichthyosis this skin disease affects around 1 in 300,000 people.

It involves the clumping of keratin filaments.

Meleda disease (MDM) or "mal de Meleda", also called Mljet disease, keratosis palmoplantaris and transgradiens of Siemens, (also known as "Acral keratoderma," "Mutilating palmoplantar keratoderma of the Gamborg-Nielsen type," "Palmoplantar ectodermal dysplasia type VIII", and "Palmoplantar keratoderma of the Norrbotten type") is an extremely rare autosomal recessive congenital skin disorder in which dry, thick patches of skin develop on the soles of the hands and feet, a condition known as palmoplantar hyperkeratosis.

Kyrle disease symptoms are chronic and have an onset during adulthood between the ages of 30 and 50 years of age. However, there were reported cases of early onset as early as 5 years of age and late onset as late as 75 years of age. The main symptom is the development of small papules into painless lesions that are surrounded by silvery scales. The lesions are painless, however, there is a chance that the patient may experience extreme urges to itch them. In time, these lesions grow up to a radius of 0.75 inch and develop into red-brown nodules with a central plug of keratin. As more lesions develop, they can come together and form larger keratotic plaques. These lesions are usually observed on the lower extremities, however, can also develop on the upper extremities, such as, the arms, the head and the neck. The only parts of the body that Kyrle disease do not form are the palms, soles, and mucous membranes. Lesions may heal spontaneously without treatment, however, new ones will develop in its place.

Other symptoms that may be observed:

- Hyperkeratotic cone-shaped papular plugs

- Hyperkeratotic verrucous plaques

- Diabetes mellitus

- Hepatic insufficiency

- Presence of albumin in the urine

- Excess sugar in the urine

Age: The mucocutaneous features of DKC typically develop between ages 5 and 15 years. The median age of onset of the peripheral cytopenia is 10 years.

Sex: The male-to-female ratio is approximately 3:1.

Physical: The triad of reticulated hyperpigmentation of the skin, nail dystrophy, and leukoplakia characterizes DKC. The syndrome is clinically heterogeneous; in addition to the diagnostic mucocutaneous features and bone marrow failure, affected individuals can have a variety of other clinical features.

Cutaneous findings:

The primary finding is abnormal skin pigmentation, with tan-to-gray hyperpigmented or hypopigmented macules and patches in a mottled or reticulated pattern. Reticulated pigmentation occurs in approximately 90% of patients. Poikilodermatous changes with atrophy and telangiectasia are common.

The cutaneous presentation may clinically and histologically resemble graft versus host disease. The typical distribution involves the sun-exposed areas, including the upper trunk, neck, and face. Other cutaneous findings may include alopecia of the scalp, eyebrows, and eyelashes; premature graying of the hair; hyperhidrosis; hyperkeratosis of the palms and soles; and adermatoglyphia (loss of dermal ridges on fingers and toes).

Nail findings:

Nail dystrophy is seen in approximately 90% of patients, with fingernail involvement often preceding toenail involvement.

Progressive nail dystrophy begins with ridging and longitudinal splitting. Progressive atrophy, thinning, pterygium, and distortion eventuate in small, rudimentary, or absent nails.

Mucosal findings:

Mucosal leukoplakia occurs in approximately 80% of patients and typically involves the buccal mucosa, tongue, and oropharynx. The leukoplakia may become verrucous, and ulceration may occur. Patients also may have an increased prevalence and severity of periodontal disease.

Other mucosal sites may be involved (e.g., esophagus, urethral meatus, glans penis, lacrimal duct, conjunctiva, vagina, anus). Constriction and stenosis can occur at these sites, with subsequent development of dysphagia, dysuria, phimosis, and epiphora.

Bone marrow failure:

Approximately 90% have peripheral cytopenia of one or more lineages. In some cases, this is the initial presentation, with a median age of onset of 10 years.

Bone marrow failure is a major cause of death, with approximately 70% of deaths related to bleeding and opportunistic infections as a result of bone marrow failure.

Pulmonary complications:

Approximately 20% of individuals with DKC develop pulmonary complications, including pulmonary fibrosis and abnormalities of pulmonary vasculature.

The recommendation is that DKC patients avoid taking drugs with pulmonary toxicity (e.g., busulfan) and that they have their lungs shielded from radiation during BMT.

Increased risk of malignancy:

Patients have an increased prevalence of malignant mucosal neoplasms, particularly squamous cell carcinoma of the mouth, nasopharynx, esophagus, rectum, vagina, or cervix. These often occur within sites of leukoplakia.

The prevalence of squamous cell carcinoma of the skin is also increased. Other malignancies reported include Hodgkin lymphoma, adenocarcinoma of the gastrointestinal tract, and bronchial and laryngeal carcinoma.

Malignancy tends to develop in the third decade of life.

Neurologic system findings: Patients may have learning difficulties and mental retardation.

Ophthalmic system findings: DKC reportedly is associated with conjunctivitis, blepharitides, and pterygium. Lacrimal duct stenosis resulting in epiphora (i.e., excessive tearing) occurs in approximately 80% of patients.

Skeletal system findings: Patients may have mandibular hypoplasia, osteoporosis, avascular necrosis, and scoliosis.

Gastrointestinal system findings: These may include esophageal webs, hepatosplenomegaly, enteropathy, and cirrhosis.

Genitourinary system findings:: Hypospastic testes, hypospadias, and ureteral stenosis are reported.

Female carriers: Female carriers of DKC may have subtle clinical features. One study showed that 3 of 20 female carriers had clinical features that included a single dystrophic nail, a patch of hypopigmentation, or mild leukoplakia.

Congenital Ichthyosiform Erythroderma (CIE), also known as Nonbullous congenital ichthyosiform erythroderma is a rare type the ichthyosis family of skin diseases which occurs in 1 in 200,000 to 300,000 births.

Naxos disease (also known as "Diffuse non-epidermolytic palmoplantar keratoderma with woolly hair and cardiomyopathy," "Diffuse palmoplantar keratoderma with woolly hair and arrhythmogenic right ventricular cardiomyopathy firstly described in Naxos island by Dr Nikos Protonotarios," and "Naxos disease") is a cutaneous condition characterized by a palmoplantar keratoderma. The prevalence of the syndrome is about 1 person in 1000 in the Hellenic islands.

It has been associated with mutations in the genes encoding desmoplakin and plakoglobin.

ILVEN is a condition that normally only affects one side of the body (unilateral). Usually the left side of patients is affected. The condition is persistent and forms along characteristic lines. It usually appears on an extremity in infancy or childhood. Altman and Mehregan described six characteristic features of ILVEN: (1) early age of onset, (2) predominance in females (4:1 female-male ratio), (3) frequent involvement of the left leg, (4) pruritus, or "itchiness" (5) marked refractoriness to therapy, and (6) a distinctive psoriasiform and inflammatory histologic appearance.

Porokeratosis may be divided into the following clinical types:

- "Plaque-type porokeratosis" (also known as "Classic porokeratosis" and "Porokeratosis of Mibelli") is characterized by skin lesions that start as small, brownish papules that slowly enlarge to form irregular, annular, hyperkeratotic or verrucous plaques. Sometimes they may show gross overgrowth and even horn-like structures may develop. Skin malignancy, although rare, is reported from all types of porokeratosis. Squamous cell carcinomata have been reported to develop in Mibelli's type porokeratosis over partianal areas involving anal mucosa. This was the first report mentioning mucosal malignancy in any form of porokeratosis.

- "Disseminated superficial porokeratosis" is a more generalized processes and involves mainly the extremities in a bilateral, symmetric fashion. In about 50% of cases, skin lesions only develop in sun-exposed areas, and this is referred to as "disseminated superficial actinic porokeratosis"

- "Porokeratosis palmaris et plantaris disseminata" is characterized by skin lesions that are superficial, small, relatively uniform, and demarcated by a distinct peripheral ridge of no more than 1mm in height.

- "Linear porokeratosis" is characterized clinically skin lesions are identical to those of classic porokeratosis, including lichenoid papules, annular lesions, hyperkeratotic plaques with central atrophy, and the characteristic peripheral ridge.

- "Punctate porokeratosis" is a skin condition associated with either classic porokeratosis or linear porokeratosis types of porokeratosis, and is characterized by multiple, minute, and discrete punctate, hyperkeratotic, seed-like skin lesions surrounded by a thin, raised margin on the palms and soles.

- "Porokeratosis plantaris discreta" is a skin condition that occurs in adults, with a 4:1 female preponderance, characterized by a sharply marginated, rubbery, wide-based papules. It is also known as "Steinberg's lesion". It was characterized in 1970.

The skin may be lightly pigmented. Skin sustaining injury may grow back permanently hypo-pigmented. In some cases, red or brown pigmentation may be present. Skin can be prone to rashes or infections and can be thick over the palms and soles. Care must be taken to prevent cracking, bleeding, and infection.

Erythrokeratodermia variabilis (also known as "erythrokeratodermia figurata variabilis", "keratosis extremitatum progrediens", "keratosis palmoplantaris transgrediens et progrediens", "Mendes da Costa syndrome", "Mendes da Costa type erythrokeratodermia", and "progressive symmetric erythrokeratoderma") is a rare autosomal dominant disorder that usually presents at birth or during the first year of life. To date, it is thought to be caused by mutations in genes encoding for connexin channels proteins in the epidermis, leading to the misregulation of homeostasis in keratinocytes.

One type is characterized by generalized, persistent, brown hyperkeratosis with accentuated skin markings, while a second type is localized, with involvement that is limited in extent and characterized by sharply demarcated, hyperkeratotic plaques.

It can be associated with GJB3 and GJB4.

It was characterized in 1925.

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.