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Eczema & Dermatitis (2)
Endogenous Dermatitis
1- Atopic dermatitis.
5- Gravitational eczema.
2- Seborrhoeic dermatitis.
6- Lichen simplex chronicus.
3- Discoid eczema.
7- Asteatotic eczema.
4- Pompholyx.
8- Pityriasis alba.
Atopic Dermatitis
Atopy
is a genetic predisposition to form excessive IgE antibodies as response
to common environmental antigens leading to prolonged and
generalized hypersensitivity and liability to manifest one or more of the
atopic diseases ( as asthma, allergic rhinitis, hay fever, eczema and
food allergies).
Atopic Dermatitis
An itchy, chronic, or chronically relapsing inflammatory skin condition. It
is characterized by itchy papules which become excoriated and
lichenified and typically have a flextural distribution. The eruption is
frequently associated with other atopic conditions in the patient himself
or other family members.
Etiopathogenesis:
Exact cause is still unknown, but it is best considered as an interplay
between genetic, immunologic, physiologic and pharmacologic factors.
1- Positive family history is found in 70% of cases, this is largely due to
genetic factors and the mode of inheritance is mainly polygenic with
some maternal imprinting.
2- Immunological abnormalities: Excessive IgE production predisposing
to excessive anaphylactic sensitivity and increased mast cell activation
and secretion of histamine and other mediators. Decreased delayed cell
mediated immunity leading to increased susceptibility to viral & fungal
infections
3- Abnormalities of essential fatty acid metabolism and decreased
amounts of lipids leading to dry skin.
4- Decreased chemotactic function of leucocytes resulting in dense
bacterial colonization and increased bacterial infections
5- Transient IgA deficiency of intestinal mucosa with increased intestinal
permeability to food allergens result in increased production of IgE.
6- Tendency of small blood vessels in atopic dermatitis towards
vasoconstriction.
7- Low itching threshold and easy skin irritability.
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Clinical features:
Onset is usually between 2-6 months of age (in 75% of cases), but it
may be delayed until childhood and adult life. Onset before 2 months is
exceptional. The cardinal feature of atopic dermatitis is itching,
“ the itch
that rashes”, and scratching may account for many of the signs. The
primary lesion is follicular papule that change into vesicle, then pustule.
The distribution and character of the rash vary with the age, thus there
are 3 clinical phases for atopic dermatitis.
Infantile phase: (2 months-2 years)
Present as itchy erythema of the cheeks and face, with fine vesicles that
may rupture and become exudative and crusted. Scalp, trunk and
extremities can also be involved but diaper area is spared. Affected
infants are usually irritable and have poor feeding and sleeping.
Childhood phase: (2years- 12years)
Lesions are usually less exudative, drier, and slightly scaly. Sites most
charecteristically involved are the elbow & knee flexures, wrists, ankles,
retroauricularfolds and sides of the neck. In 2/3 of cased spontaneous
remission occur by 12years, while 1/3 of cases change into
Adult phase:
Lesions are usually dry, thick, lichenified, and hyperpigmented involving
the same (but larger) areas as childhood phase. This phase may
persist for life.
Diagnosis:
There is no definite sign or symptom and diagnosis is based on
collecting criteria. Several sets of criteria have been developed based
on the initial criteria proposed by (Hanifin and Rajka) in 1980.
American Diagnostic Criteria (AAD)
Atopic Dermatitis Work Group of American Academy of Dermatology
(AAD) presented the following recommendation of diagnostic criteria
Essential Features
—Must Be Present
1. Pruritus
2. Eczema (acute, subacute, chronic)
A-Typical morphology and age-specific patterns
i. Infants and children
—facial, neck, and extensor involvement
ii. Any age group
—current or previous flexural lesions
iii. All groups
—sparing of groin and axillary regions
B-Chronic or relapsing course
Important Supporting Features (Seen in Most Cases)
1. Early age of onset
2. Personal or family history of atopic disease
3. IgE reactivity
4. Generalized xerosis
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Exclusionary Conditions
1.Scabies
2. Seborrheic dermatitis
3. Allergic or irritant CD
4. Ichthyoses
5. Cutaneous T-cell lymphoma (CTCL)
6. Psoriasis
7. Photodermatoses
8. Immunodeficiency with cutaneous findings
9. Erythroderma of other etiologies
Treatment:
1- General measures: explanation, reassurance and encouragement.
2- Avoidance of triggering factors: excessive bathing, irritating soaps,
woolen clothes, extremes of cold and heat, and emotional stress.
3- Topical therapy:
• Topical corticosteroids in appropriate strength and base to suppress
inflammation, “if lesion is dry, wet it by ointment & if wet, dry it by
lotions”.
• Regular use of emollient especially after bathing to increase skin
hydration. ex. Vaseline or Zinc oxide ointments.
• Topical immunosupressants: tacrolimus ointment is safe with slight
burning sensation being most common side effect.
4- Systemic therapy:
• Sedative antihistamines to control pruritus and give sedation.
• Systemic corticosteroids to control acute, generalized and severe
cases.
• Antibiotic for treatment and prophylaxis of secondary bacterial
infections.
• Photothrapy (PUVA or UVB) is often helpful for severe cases.
Seborrhoeic Dermatitis
A distinctive type of eczema characterized by yellowish greasy scaling
over red inflammed skin affecting the seborrheic areas of the body
(mainly the scalp, eyebrows, eyelids, nasolabial folds, beard,
moustache, external auditory canal, retroauricular fold, sternal areas,
shoulders, interscapular area, axillae, & groins). It usually start with
puberty and exacerbate in winter.
Etiopathogenesis:
It is due to the effect of pityrosporum ovale overgrowth, (a yeast like
fungus regarded as part of normal skin flora), which act on TG present
in the sebum to produce FFA that is very irritant to skin resulting in
itching, erythema, scale & inflammation.
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Clinical features:
It may presesnt in many ways:
1- A red scaly or exudative eruption of the scalp, ears, face and
eyebrows. May be associated with blepharitis and otitis externa.
2-
Dry scaly “petaloid” lesions of the presternal and interscapular areas.
There may also be extensive follicular papules or pustules on the trunk
(pityrosporum folliculitis).
3- Intertrigenous lesions of axillae, inframmamary, umbilicus, inguinal
folds, ano-genital areas, and even under spectacles or hearing aids.
4- Seborrheic dermatitis may affect infants up to 3 months of life and
present as cradle cap, flexural eruption, or erythroderma.
Treatment:
Combined
topical
steroid
and
topical
antifungal
preparation. Treatment is suppressive rather than curative.
Discoid eczema
A common pattern of endogenous eczema characterized by multiple,
well defined, coin-shaped, vesicular or crusted, highly itchy plaque
usually less than 5 cm in diameter. It classically affects the extensor
surface of limbs of middle aged and tends to persist for months.
Emotional stress is important causative factor. Topical steroid-antibiotic
mixture does better than either separately.
Pompholyx
A special form of endogenous eczema characterized by development of
recurrent bouts of deep seated vesicles or larger blisters appear on the
palms, fingers and/or the soles of adult. Bouts lasting a few weeks &
recur at irregular intervals. Secondary infection and lymphangitis are
recurrent problem. Heat, emotional upsets, nickel ingestion, or fungal
infection may trigger pompholyx.
Treatment: K+pemaenganate soaks followed by very potent steroid. A
course of systemic steroid and appropriate antibacterial may be
needed.
Gravitational eczema
A chronic itchy, patchy eczematous condition of the lower legs
secondary to venous hypertension and varicosity. It is often associated
with signs of venous insufficiency (edema, red or bluish discoloration,
loss of hair, small patches of atrophy, induration, hemosiderin
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pigmentation and ulceration). Secondary allergic sensitization to topical
antibiotics and persistent ulceration may complicate the condition.
Treatment: correct the cause, eliminate edema by elevation & pressure
bandage, use mild-moderate topical steroid. Avoid topical antibiotics
and very potent steroids.
Neurodermatitis
(Lichen Simplex Chronicus)
A usually single itchy fixed plaque of lichenified eczema due to repeated
rubbing and scratching of accessible areas, as a habit or in response to
stress. The favorite sites are the nape of the neck of women, the legs in
men, and the anogenital area in both sexes. Lesions may resolve with
treatment but tend to recur either in the same place or elsewhere.
Potent topical steroids under occlusion may break the scratch itch cycle
and sedative antihistamines are often needed.
Asteatotic Eczema
Often unrecognized, this common and itchy pattern of eczema occurs
usually on the legs of elderly patients who have dry skin and tendency
to chap. Removal of surface lipids by over-washing, low humidity of
winter and the use of diuretics are contributory factors. Against a
background of dry skin, a network of fine red superficial fissures creates
a “crazy paving” appearance. Treatment: stop irritants, restrict bathing,
topical steroids in ointment base, then use unmedicated emollients daily
to prevent recurrence.
Pityriasis Alba
May be part of atopic dermatitis or not. It usually affect children aged
3-15 years, affecting exposed parts mostly the face, chest, sides of
neck, upper trunk and extrimities. It present as single or multiple
hypopigmented patches (preceded by transient erythematous stage)
and covered with fine whitish scale. Treatment: reassurance about self
limiting nature of the condition, restriction of excess soap use, mild
topical steroid ointment and emollients.