Dermatología Pediatrica

Lawrence Schachner; Alyssa Feiner; Sam Camisulli

The "Clinical Snapshot" series provides a concise examination of a clinical presentation including history, treatment, patient education, and nursing measures. Using the format here, you are invited to submit your "Clinical Snapshot" to Dermatology Nursing.

Epidermolysis bullosa (EB) is the term given to a group of inherited mechanobullous disorders involving blistering of the skin and sometimes mucous membranes in response to minor frictional trauma. There are three types of EB: simplex, junctional, and dystrophic. Each form has a specific cleavage plane within the epidermal-dermal basement membrane zone, as well as specific clinical manifestations. Each form of EB has distinguishing pathophysiology, mode of inheritance, and prognosis (Tidman & Garzon, 2003).


In all forms of EB simplex (EBS), blisters form by cytolysis of the infranuclear portion of the basal keratinocytes. Currently there are approximately seven variants of EBS, each with specific clinical manifestations. EBS Weber-Cockayne is a variant with blistering confined primarily to the palms and soles. EBS Koebner is a different variant with widespread blistering at sites of friction. EBS Dowling-Meara is a form of the disease with neonatal widespread blistering progressing to blistering in characteristic clusters. EBS is inherited in an autosomal dominant manner with a few exceptions. The prevalence of EBS in 2001 based on a Scotland study was determined as 33.2 cases per million of the population, and the incidence between 1960 and 1999 was 34.4 per million live births. The figures from the National EB Registry are 4.6 cases per million of the population and 10.75 per million live births. The Weber-Cockayne and Koebner variants account for the majority of EBS cases. These variants as well as Dowling-Meara (the most severe type of EBS) and mottled pigmentation variants are caused by mutations in the genes encoding keratins 5 or 14. These are the genes that constitute and are expressed by the cytoskeleton of basal keratinocytes (Tidman & Garzon, 2003).

Junctional epidermolysis bullosa ( JEB) is a variant of EB where the cleavage plane is in the lamina lucida of the epidermal basement membrane. The usually lethal form of JEB is called JEB-Herlitz. All types of JEB are inherited in an autosomal recessive manner. JEB is the rarest form of EB with a prevalence of 0.3 cases per million of the population and an incidence of 3.2 new cases per million live births. The U.S. equivalent figures are 0.44 and 2.04. The type, location, and severity of blistering varies based on the type of JEB. JEB is usually due to mutations in genes encoding laminin 5, which morphologically are the anchoring filaments that cross the lamina lucida (Tidman & Garzon, 2003).

Dystrophic EB (DEB) is a result of a mutation in the gene that encodes type VII collagen, the anchoring fibrils that unite the lamina densa with the underlying elements of the papillary dermis. The clinical severity of DEB as well as in all the other major variants of EB is based on the type of mutation, where the mutation is within the protein molecule, as well as other mutations that may be clinically silent. The bullae in DEB usually heal with scarring and transient milia, and are usually associated with some degree of nail dystrophy. DEB may be inherited as autosomal dominant or autosomal recessive conditions. The prevalence based on the Scottish study is 24.6 cases per million of the population (2.4 cases per million in the United States) and the inci-dence is 26.4 new cases per million live births. Most of the cases are the dominant form of DEB. The clinical picture in each type varies. In dominant DEB, usually bullae manifest over acral bony prominences. During healing, milia develop with subsequent atrophic scarring. Thickened nail plates with scarring and eventual loss of the nail is seen. There may be oral bullae and involvement of the gastrointestinal tract as well (Tidman & Garzon, 2003).

There is no specific treatment for any of the variants of EB. Care for patients with EB is fundamentally preventative and symptomatic (see Table 1 ). The current treatment strategies focus on preventing the formation of new blisters, preventing and treating infections, facilitating wound healing, providing nutritional support, managing extracutaneous complications, and maintaining and providing a strong psychological support system to patients and family members (Tidman & Garzon, 2003).

References

Tidman, M., & Garzon, M. (2003). Vesiculobullous disease. In L.A. Schachner & R.C. Hansen (Eds.), Pediatric dermatology (3rd ed.) (pp. 683-692). St. Louis, MO: Mosby.


Lawrence Schachner , MD , is a Professor of Dermatology and Pediatrics, and Director, Division of Pediatric Dermatology, University of Miami School of Medicine, Miami, FL.

Alyssa Feiner , MD , is a Medical Student, University of Miami School of Medicine, Miami, FL.

Sam Camisulli , MD , is a Dermatology Resident, University of Toronto, Toronto, Ontario, Canada