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

• FAH (Focal Acral Hyperkeratosis)
• Marginal Palmoplantar Keratoderma
• PPK3 without Elastoidosis

What is Focal Acral Hyperkeratosis? (Definition/ Background Information)

• Focal Acral Hyperkeratosis (FAH) is a rare benign skin condition, wherein there is a formation of tiny papules or plaques on the hands and feet. FAH is a genetic disorder that may be inherited in an autosomal dominant manner
• The skin condition is a type of palmoplantar keratoderma. Palmoplantar keratoderma (PPK) is a benign condition, wherein there is thickening of skin (keratoderma) of the palms and/or soles
• The signs and symptoms of Focal Acral Hyperkeratosis often develop gradually and the skin on the hands and feet are affected. Some cases are mild, while some may be severe
• A diagnosis of Focal Acral Hyperkeratosis can be made by clinical exam, skin exam, and various other diagnostic tools including dermoscopy and wood’s lamp examination
• Currently, there is no effective treatment for Focal Acral Hyperkeratosis. Nevertheless, the treatment of the affected skin may include the use of moisturizers, topical creams, and skin softeners. The prognosis depends upon the severity of the presenting symptoms

Who gets Focal Acral Hyperkeratosis? (Age and Sex Distribution)

• Focal Acral Hyperkeratosis may be observed in a wide age range of individuals. The manifestation of symptoms is mostly noted by or before the age of 20 years
• The condition affects both males and females
• Initially it was thought that FAH was confined to certain individuals of Afro-Caribbean and Arabic descent. However, studies indicate that dark-skinned individuals are more prone to FAH
• Recent studies have shown that this skin condition can be seen in other races worldwide too

What are the Risk Factors for Focal Acral Hyperkeratosis? (Predisposing Factors)

• The main risk factor for Focal Acral Hyperkeratosis is a positive family history of 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 Focal Acral Hyperkeratosis? (Etiology)

Focal Acral Hyperkeratosis is a genetic disorder with a hereditary origin, in many cases.

• It is caused by genetic mutations, which are passed down through families in an autosomal dominant pattern
• In some cases, the condition is sporadic, indicating that a prior family history is not present

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 function 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 Focal Acral Hyperkeratosis?

The signs and symptoms associated with Focal Acral Hyperkeratosis (FAH) manifest gradually and may include:

• The presence of very small papules or plaques on the skin of the hands and feet. Typically, the underlying skin is not affected
• Usually both hands and feet are involved
• Hair and nails are not affected
• In some individuals, the condition is mild; while in others, it may be severe
• Within families, the severity of signs and symptoms may vary the among family members

The presentation of FAH is very similar to acrokeratoelastoidosis (another skin condition of the hands and feet). It is generally difficult to differentiate between the two conditions based on clinical signs and symptoms alone.

How is Focal Acral Hyperkeratosis Diagnosed?

The diagnosis of Focal Acral Hyperkeratosis (FAH) may involve:

• A complete evaluation of medical history (including family medical history) along with a thorough examination of the skin lesions by a dermatologist
• 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
• Electron microscopy studies is helpful in differentiating FAH from acrokeratoelastoidosis
• Skin biopsy: A skin 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
• The following skin conditions may be eliminated by performing a differential diagnosis, prior to arriving at a definite diagnosis:
  • Acrokeratoelastoidosis of Costa
  • Acrokeratosis verruciformis of Hopf
  • Darier (or Darier’s) disease
  • Epidermodysplasia verruciformis
  • Lichen planus
  • Punctate palmoplantar keratoderma
  • Punctate sporokeratosis
  • Verruca plana or plane wart
  • Xanthoma

Note: A skin biopsy may show no dermal changes i.e., Focal Acral Hyperkeratosis does not have breakdown of elastic fibers (elastorrhexis), which is crucial in establish a diagnosis of FAH, during a skin biopsy.

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 Focal Acral Hyperkeratosis?

Complications associated with Focal Acral Hyperkeratosis may include the following:

• Emotional stress due to the skin condition
• Cosmetic concerns
• The skin condition may get progressively worse until puberty (age 12-13 years)

How is Focal Acral Hyperkeratosis Treated?

It is generally difficult to treat Focal Acral Hyperkeratosis; however, the skin symptoms may be addressed through treatment measures such as:

• Use of moisturizing creams and lotions; use of ointments containing vitamin D
• Use of topical and systemic retinoids
• Administration of keratolytics (medicine containing salicylic acid)

How can Focal Acral Hyperkeratosis be Prevented?

Currently, Focal Acral Hyperkeratosis 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 and acquired genetic disorders such as FAH

What is the Prognosis of Focal Acral Hyperkeratosis? (Outcomes/Resolutions)

The prognosis of Focal Acral Hyperkeratosis (FAH) may depend on the severity of the signs and symptoms. In most cases, the prognosis is good with appropriate treatment.

• However, in general, FAH is difficult to treat and may present treatment challenges
• Regular follow up visits with the healthcare provider are important and encouraged

Additional and Relevant Useful Information for Focal Acral Hyperkeratosis:

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.