DERMATITIS ARTEFACTA
DESENSITIZATION
in contact with the skin. Common caus-
es are detergents, nickel, certain plants,
and cosmetics. It may be treated with
topical corticosteroids. A patch test (see
skin tests
)
may be done to identify the
cause. Photodermatitis occurs in peo-
ple whose skin is abnormally sensitive
to light. A cluster of spots or blisters
occurs on any part of the body exposed
to the sun (see
photosensitivity)
.
dermatitis artefacta
Any self-induced
skin condition. It may range from a mild
scratch to extensive mutilation.
dermatitis herpetiformis
A chronic skin
disease in which clusters of tiny, red,
intensely itchy blisters occur in a sym-
metrical pattern, most commonly on the
back, elbows, knees, buttocks, and scalp.
It usually develops in adult life and is
believed to be related to
coeliac disease.
dermatology
The branch of medicine
concerned with the
skin
and its disorders.
dermatome
An area of skin supplied
with nerves by a pair of spinal nerve
roots from the cervical (C2-C8), thoracic
DERMATOME
Cervical region
(nerve C5)
Cervical region
(nerve C6)
Lumbar region
(nerves L1-L5)
Sacral region
(nerve S3)
Sacral region
(nerve S4)
Sacral
region
(nerve S5) _
Sacral region
(nerve S
Lumbar region
(nerve L
Lumbar region
(nerve L3)
Sacral region
(nerve S2)
Cervical region
(nerve C2)
Cervical region
(nerve C3)
Cervical region
(nerve C4)
Thoracic region
(nerves T1-T12)
region
(nerve C7)
Cervical region
(nerve C8)
Lumbar region
(nerve L2)
Lumbar region
(nerve L4)
Lumbar region
(nerve L5)
(T1-T12), lumbar (L1-L5), and sacral
(S1-S5) regions. The entire body surface
is an interlocking pattern of dermatomes,
which is similar from one person to an-
other. Abnormal sensation in a dermatome
signifies damage to a particular nerve
root, commonly due to a
disc prolapse
.
dermatome, surgical
A surgical in-
strument for cutting varying thicknesses
of skin for use in skin grafting.
dermatomyositis
A rare
autoimmune
disorder
in which the muscles and skin
become inflamed. It causes a skin rash
first on the bridge of the nose and cheeks,
followed by a purple discoloration on the
eyelids and sometimes a red rash on
the knees, knuckles, and elbows. Muscles
become weak, stiff, and painful, particu-
larly those in the shoulders and pelvis.
Treatment is with
corticosteroid drugs
and/or
immunosuppressant drugs
and
physiotherapy
.
In about 50 per cent of
cases, full recovery occurs after a few
years. The remainder have persistent
muscle weakness. In about 20 per cent,
it eventually affects the lungs and other
organs and may be fatal.
dermatophyte infections
A group of
common fungal infections affecting the
skin, h air, and nails, also known as
tinea
and, popularly, as ringworm.
dermis
The inner layer of the
skin
.
dermographism
Abnormal sensitivity
of the skin to mechanical irritation, to
the extent that firm stroking leads to the
appearance of itchy weals. The condi-
tion is a form of
urticaria
. It is most
common in fair-skinned people with a
tendency to allergic conditions.
dermoid cyst
A noncancerous tumour
with a cell structure similar to that of
skin. It contains hairs, sweat glands, and
sebaceous glands. Dermoid cysts may
also contain fragments of cartilage, bone,
and even teeth. The cysts may occur in
various parts of the body. Ovarian der-
moid cysts account for
10
per cent of all
ovarian tumours. Only rarely do they
become cancerous. In the skin, dermoid
cysts most commonly occur on the
head or neck. Surgical removal is usual-
ly recommended. (See also
teratoma
).
dermoid tumour
See
dermoid cyst
.
desensitization
A technique, used in
behaviour therapy
for treating
phobias
,
167
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