Description, Causes and Risk Factors:
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.
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 ca
n 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.
Mutations in the KRT1 or KRT10 genes are responsible for epidermolytic hyperkeratosis. These genes provide instructions for making proteins called keratin 1 and keratin 10, which are found in cells called keratinocytes in the epidermis (outer layer of the skin). The tough, fibrous keratin proteins attach to each other and form fibers called intermediate filaments, which form networks and provide strength and resiliency to the epidermis.
Mutations in the KRT1 or KRT10 genes lead to changes in the keratin proteins, preventing them from forming strong, stable intermediate filament networks within cells. Without a strong network, keratinocytes become fragile and are easily damaged, which can lead to blistering in response to friction or mild trauma. It is unclear how these mutations cause the overgrowth of epidermal cells that result in hyperkeratotic skin.
Epidermolytic hyperkeratosis is an autosomal dominant hereditary disorder. In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed "dominating" the other normal gene and resulting in the appearance of the disease. The risk of transmitting a dominant disorder from affected parent to offspring is fifty percent for each pregnancy
. Some cases of epidermolytic hyperkeratosis are caused by a spontaneous mutation.
The disease occurs in approximately 1 in 100,000 individuals. There is no sex predilection.
Infants with epidermolytic hyperkeratosis may be born with red, blistering and denuded skin with visible areas of skin thickening. Over time, there is a gradual decrease in blistering, but an increase in the severity of the scaling and skin thickening. Scales tend to form in parallel rows of spines or ridges. A generalized erythroderma (redness of the skin) may be present in some individuals. Skin infections with common bacteria can be a problem. Heat intolerance is common. A palmoplantar keratodermia may be present and can be so severe as to limit ambulation and hand function.
The diagnosis of epidermolytic hyperkeratosisinvolves:
Laboratory evaluation: Apart from a chosen therapy or bacterial culture, no general laboratory studies need to be done for suspected infection. Keratin defect studies are performed on buccal swabs or blood. If a mutation is identified in an affected individual, mutation-specific testing for relatives and prenatal diagnosis can also be done.
Other Procedures: Skin biopsy
is very helpful with histological findings which confirm a diagnosis. Prenatal diagnosis can be made through chorionic villus sampling (CVS) analysis of amniotic cells or fetal skin biopsies.
Keeping the skin properly moisturized is perhaps the most important step in the management of symptoms if you are affected by epidermolytic hyperkeratosis. Topical emollients need to be used regularly in order to prevent scaling. After the skin begins to scale, you are at increased risk for bacterial infections of the skin. Taking frequent long baths is another recommendation for proper skin care if you have this condition.
Anti-inflammatory medications are used to control any swelling or inflammation of the affected skin. Oral retinoids such as isoretinoin are used to manage the symptoms of epidermolytic hyperkeratosis. Isotretinoin is derived from Vitamin A and is known to be the miracle drug.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.