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A child presents with recurrent unexplained blister formation, primarily on the hands and feet that develop into mild ulcerations and heal without scarring. Smaller erosions and vesicles are present on the elbows, arms and shoulders, and the patient has lost several fingernails and toenails. Family history is negative for psoriasis and atopy. What’s your diagnosis?
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Epidermolysis bullosa simplex (EBS) is a group of inherited skin conditions in which the skin blisters in response to minor injury, heat, rubbing or scratching. Mutations in genes involved in keratin production, specifically KRT5 and KRT14, are the most common cause of EBS, but researchers have implicated more than 10 genes in the molecular basis of the disorder.
EBS affects approximately 1 in 30,000 to 50,000 people each year, and patients can experience a wide array of signs and symptoms depending on disease severity. These range from mild blisters on the hands and feet without scarring to severe widespread blistering that can result in life-threatening complications. The following specific symptoms have been reported with EBS:
- Deformity or loss of fingernail and toenails;
- Hyperkeratosis and milia;
- Scarring alopecia;
- Excessive sweating;
- Dental abnormalities;
- Internal blistering on the throat, esophagus, upper airway, stomach intestines and urinary tract.
Disease severity and symptom onset depend on the type of EBS: Weber-Cockayne type, Keobner type or herpetiform Dowling-Meara type.
Patients with the Weber-Cockayne subtype, the most common form of EBS, can experience disease onset anytime in childhood or adulthood. Localized thick-walled blisters on the feet and hands, which usually occur in children after they begin to walk or in adults after strenuous exercise, characterize the disorder. Secondary infection of the blistered lesions is a common complication with this type of EBS.
Keobner subtype EBS onset is at birth to early infancy and occurs as generalized blisters that affect the hands, feet and extremities. Nails, teeth and oral mucosa are generally not affected.
Dowling-Meara EBS has a generalized distribution of variable lesions, transient milia and grouped herpetiform blisters that can involve the oral mucosa, trunk and proximal extremities. Lesions heal without scarring and fingernails and toenails may shed and grow back with dystrophy. After the age of 6 or 7 years, children may develop hyperkeratosis of the palms and soles.
Complications can include secondary skin infection, sepsis, deformities, malnutrition, anemia, eye disorders, increased risk for squamous cell carcinoma and death.
Laboratory tests are necessary to confirm EBS diagnosis and can include skin biopsy with light, elctron or immunoflourescene microscopy or cell culture, and blood samples should be obtained from family members to perform genetic testing.
There is no cure for EBS. Treatment depends on severity and involves preventing pain, secondary infections and complications. Clinicians should counsel patients and family members on skin and wound care, including performing blister drainage with a sterile needle, as well as proper application of antibiotic ointments, petroleum jelly and wound dressing.
Advise parents and caregivers to maintain a gentle touch, keep households at a consistently cool temperature, keep the patient’s fingernails cut short, chose soft materials for clothing and avoid participation in rough activities.
Skin grafts are an option for patients whose wounds do not heal. Surgery may be necessary to correct contractures and other deformities that may interfere with a patient’s normal range of motion.
1. Freedberg IM, Isin AZ, Wolff K, et al. Fitzpatrick’s Dermatology in General Medicine (5th ed.). 1999. New York: McGraw-Hill.