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Erythema multiforme
(EM)
Definition
Erythema multiforme is a serious
of acute, self-limited, recrudescent
and inflammatory dermatopathy
characterized by erythema, papula
and blister, which involves of skin and
mucosa.
Etiopathogenisis
1. Hypersensitivity with infection:
virus, mycoplasma, bacterium,
mycetes or protozoon
2. Food allergy
3. Climatic change
4. Drug allergy (drug eruption)
5. Connective tissue diseases
Pathogenesis
Possible mechanism is
hypersensetivity of small
vesseles to some sensitizers.
Clinical Manifestation
1. Lesions ： erythema, papula, blister,
bulla or blood bister. The mark lesion is
iris-like lesion.
2. Distribution：
Predilection sites include back of hand,
dorsum of foot, face and cervix. Mucosa
can be involved.
Idio-EM:etiology unknown
Symptomatic EM:etiology
known
Grouping:according to
appearance
Macule type
Papule type
Blister type
Macule Type
Bright red edematous macule ,round or
orbicular-ovate. The macule may expand
peripherad with gloom prunosus center and
ruby-red margin. If central edema is
absorbed and depressed like a disk, the lesion
will offer ring shape. Several ring-shape
lesion may confluens together to
polynucleation.
Papule Type
It’s the most common type. Because of
serosity exudation,the papule swell up to the
surface of skin , dome shape and soybean
size，sometimes like wheal.
Blister Type
Severe exudation. The center of rash is
blister ,surrounding with kermesinus areola.
It’s called iris-like lesion if different colors
and sizes of loops overlapped，like iris. It is
more serious when bulla or blood blister
occur.
Mucosal Damage
General damage is gray patch,
then blister, erosion, bleed, ulcer
and scab. When in eye,
conjunctivitis is more frequent.
Histopathology
Early lesions include dropsy of upper
stratum of dermis, vasodilatation
swell of vessel wall, and perhaps, fibrinoid
degeneration. The dermal infiltrate is largely
lymphocyte, eosinophile granulocyte,
neutrophil. The blisters lie in the dermal-
epidermal junction, or in basal cells.
Laboratory examination
 Hemogram: anemia, leukocytosis
(sometimes leukopenia ) ,eosinophile
granulocyte increase
ESR: increase
Hemoculture: negative
Sometimes proteinuria and hematuria.
Diagnosis and
Differential Diagnosis
Evidence for diagnosis：
1. Pleomorphism
2. Predilection: distal extremities and face, etc.
3. Both skin and mucosa could be involved.
EM must be distinguished from herpetiform
dermatitis and pemphigoid.
Treatment
Medication:
1. Search for reasons so that corresponding treatment
can be given. Stop all doubtful allergized medicine.
2. The treatment of EM is determined by type,
pathogenetic condition and diseased region.
Antihistamine drugs are generally chosen.
3. In severe cases, systemic steroid combined with
antibiotics may be used, even supportive care such as
blood transfusion or high protein diet when necessary.
External:
1. Skin erythema , papula： calamine lotion or catapasm:
Bulla: suck the liquid
Erosion and effusion : hydropathic compress with 3％
boric acid solution or Pow. Neomgcin-coal-tar.
2. Oral mucosa erosion: Rinse the mouth with 2％
NaHCO3，then repaste Pow.Qingdai, Pow. Xilei,
Cream. mucosal Ulcer or dental ulcer film coating , etc.
3. Ocular damage: Flush with NS，then apply oculentum
acidi borici or Cortisone eyewater, etc. It is necessary to
prevent conglutination, secondary infection ,corneal ulcer
and perforation, etc.