What are the other Names for this Condition? (Also known as/Synonyms)

• Diffuse Nonepidermolytic Palmoplantar Keratoderma
• Palmoplantar Keratoderma Diffusa Circumscripta
• Vörner (Unna-Thost) Palmoplantar Keratoderma

What is Unna-Thost Palmoplantar Keratoderma? (Definition/Background Information)

• Unna-Thost Palmoplantar Keratoderma is an uncommon form of hereditary diffuse palmoplantar keratoderma that is transmitted in an autosomal dominant manner. The condition manifests during early childhood/infancy, and is characterized by symmetrical skin thickening confined to the palms and soles
• Hereditary diffuse palmoplantar keratoderma is a type of palmoplantar keratoderma (PPK) caused by genetic mutations. PPK is a benign skin condition, wherein there is thickening of skin (keratoderma) of the palms and/or soles. PPK is considered to be a pattern of skin findings and not a condition in itself. The abnormal skin thickening can be focal (localized), widespread (diffused), or punctate type (appearing as tiny bumps)
• The skin signs and symptoms of Unna-Thost Palmoplantar Keratoderma are typically progressive resulting in severe difficulty in performing simple daily tasks with the hands and feet. The treatment involves the use of moisturizers, skin softeners, and systemic medications. The prognosis of Unna-Thost PPK is determined on a case-by-case basis

Who gets Unna-Thost Palmoplantar Keratoderma? (Age and Sex Distribution)

• Unna-Thost Palmoplantar Keratoderma is a rare congenital disorder; the signs and symptoms are predominantly noted in infants within the first 12 months of life
• However, occasionally, the manifestation of symptoms occur during late childhood/adolescence or even into adulthood
• The condition affects both males and females; some reports indicate a slight preference for males
• It is seen worldwide, and all racial and ethnic groups may be affected

What are the Risk Factors for Unna-Thost Palmoplantar Keratoderma? (Predisposing Factors)

• The risk factor for Unna-Thost Palmoplantar Keratoderma includes a positive family history of the condition
• Children born to consanguineous partners or spouses have a higher risk for the condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Unna-Thost Palmoplantar Keratoderma? (Etiology)

• Unna-Thost Palmoplantar Keratoderma is caused by genetic abnormalities which are passed down (through families) in an autosomal dominant pattern
• It is caused by mutations involving keratin 1 and keratin 9 genes (KRT1 and KRT9 genes)

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly functioning gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition, or pass it on to their offspring.

What are the Signs and Symptoms of Unna-Thost Palmoplantar Keratoderma?

In general, the signs and symptoms associated with Unna-Thost Palmoplantar Keratoderma may include:

• Young children present red palms and red soles
• This forms abnormally-thickened skin on the palms and soles, which is symmetric in presentation
• The skin thickening involves the entire palm and sole (diffused); the fingers and toes are usually affected
• A yellowish-waxy skin appearance is noted
• Grooves and deep cracks may appear on the palms and soles, due to drying and hardening of the skin layers
• Formation of fluid-filled blisters (dyshidrotic eczema)
• Unna-Thost PPK is a nonepidermolytic condition, meaning there is no damage to the epidermal layer in this condition
• No itching is noted, but there may be pain and inflammation
• Hyperhidrosis, excessive sweating, of the palms and soles is present
• The skin on top of the hands or feet are not affected, but the nails may be affected
• Cold winters can aggravate the skin condition and cause relapses
• Normal activities that involve the use of one’s hands and feet may be severely affected
• No other body organs or systems are known to be affected

How is Unna-Thost Palmoplantar Keratoderma Diagnosed?

The diagnosis of Unna-Thost Palmoplantar Keratoderma may involve:

• A complete evaluation of medical history along with a thorough examination of the skin lesions by a dermatologist
• The healthcare provider may also ask many questions related to the individual’s age, family medical history, current medications, cosmetics, body lotions used, other medical conditions, infections, etc.
• Blood tests that may include complete blood count (CBC) test, basic metabolic panel, and liver function test (LFT)
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Molecular genetic testing to identify the gene involved
• Skin biopsy: A skin tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Unna-Thost Palmoplantar Keratoderma?

The complications associated with Unna-Thost Palmoplantar Keratoderma may include:

• Emotional stress
• Cosmetic concerns
• Secondary bacterial and fungal infections due to presence of deep fissures; this can present a foul smell
• Onychomycosis, or nail fungal infection
• Use of hands and feet for regular activities (such as eating or walking) may be severely compromised
• Reduced quality of life
• Lack of treatment response, and treatment complications

How is Unna-Thost Palmoplantar Keratoderma Treated?

There is no cure for Unna-Thost Palmoplantar Keratoderma, and the condition is managed through symptomatic (skin softening) treatment, which may involve the following measures:

• Use of moisturizing creams and lotions
• Use of oral medication, such as acitretin, and systemic retinoids
• Administration of keratolytics (medicine containing salicylic acid or lactic acid)
• Phototherapy
• Surgical debridement (removal of thickened skin)

Regular follow up visits with the healthcare provider is important and recommended.

How can Unna-Thost Palmoplantar Keratoderma be Prevented?

Currently, Unna-Thost Palmoplantar Keratoderma is a genetic disorder that cannot be prevented. However, the following may be considered:

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited genetic disorders such as hereditary palmoplantar keratoderma

What is the Prognosis of Unna-Thost Palmoplantar Keratoderma? (Outcomes/Resolutions)

The prognosis of Unna-Thost Palmoplantar Keratoderma is dependent upon the severity of the signs and symptoms, associated complications, and treatment response.

• Individuals with mild conditions have better prognosis than those with severe symptoms and complications. Typically, the prognosis may be assessed on a case-by-case basis
• In many individuals, Unna-Thost PPK is a lifelong chronic and relapsing condition that can severely affect the quality of life

Additional and Relevant Useful Information for Unna-Thost Palmoplantar Keratoderma:

Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that could potentially worsen the condition.