Encyclopedia of Health and Medicine

E
eczema
See DERMATITIS.
ecchymosis The clinical term for a bruise.
Ecchymosis occurs when there is bleeding into the
layers of the SKIN, causing discoloration and sometimes
swelling and discomfort. The injured area
typically undergoes several, and sometimes vivid,
color changes during the stages of HEALING. Ecchymosis
usually results from trauma to the tissue,
such as a blow. Ecchymosis may also occur as a
symptom of bleeding disorders, LEUKEMIA, LIVER
disease, and other health conditions. Ecchymosis
that develops without known trauma warrants a
doctor’s evaluation to determine the underlying
cause.
See also BLACK EYE; PETECHIAE; PURPURA.
epidermolysis bullosa The collective term for a
group of inherited SKIN disorders that result in blisterlike
formations (bullae) on the skin. Severity
can range from mild (a few bullae) to debilitating
(bullae covering large areas of the body). Dermatologists
classify epidermolysis bullosa according to
the layer of the skin where the bullae originate.
There are three general types of epidermolysis
bullosa:
• Epidermolysis bullosa simplex involves the epidermis,
the skin’s outermost layer, and usually
results from an autosomal dominance inheritance
pattern for the gene that encodes keratin
production.
• Junctional epidermolysis bullosa involves the
basement membrane, a thin layer of cells that
separates the epidermis and the dermis, and
usually results from an autosomal recessive
inheritance pattern for the gene that encodes
protein structures which connect the epidermis
and dermis through the basement membrane.
• Dystrophic epidermolysis bullosa involves the
basement membrane as well, occurring in
either an autosomal dominance or a recessive
inheritance pattern for the gene that encodes
collagen formation.
In all types, bullae form with friction or irritation
to the skin. In the junctional and dystrophic
types, this includes the mucous membranes of the
gastrointestinal and genitourinary tracts. Healed
bullae typically leave scars. The severity of symptoms
and disease vary according to the type and,
with dystrophic epidermolysis bullosa, the inheritance
pattern (dominant or recessive). At present
there is no cure for any type of epidermolysis bullosa.
Symptoms and Diagnostic Path
The bullae of epidermolysis bullosa are uniquely
characteristic and typically begin in infancy. The
skin is frail and may BLISTER or tear upon touch or
contact with clothing and bedding. The bullae of
epidermolysis bullosa simplex generally affect only
the palms of the hands and soles of the feet. The
bullae of other types may affect mucous membranes
throughout the body. The repeated blistering
and HEALING of junctional and dystrophic types
causes scarring and tissue damage that often
results in deformities. People who have junctional
or dystrophic epidermolysis bullosa may also have
defects of the tooth enamel and the NAILS, or be
missing fingernails or toenails.
The diagnostic path includes examination of
the entire skin surface and mucous tissues with
biopsy to determine the level of tissue separation
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