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 some-
times swelling and discomfort. The injured area
typically undergoes several, and sometimes vivid,
color changes during the stages of HEALING. Ecchy-
mosis 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 SKINdisorders that result in blis-
terlike formations (bullae) on the skin. Severity
can range from mild (a few bullae) to debilitating
(bullae covering large areas of the body). Derma-
tologists 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 epi-
  dermis, the skin’s outermost layer, and usually
  results from an autosomal dominance inheri-
  tance 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 irrita-

tion 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 symp-

toms and disease vary according to the type and,

with dystrophic epidermolysis bullosa, the inheri-

tance pattern (dominant or recessive). At present

there is no cure for any type of epidermolysis bul-

losa.

Symptoms and Diagnostic Path

The bullae of epidermolysis bullosa are uniquely

characteristic and typically begin in infancy. The

skin is frail and may BLISTERor 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 mem-

branes throughout the body. The repeated blister-

ing and HEALINGof 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

154