ALLERGY

- An altered state of reactivity tocommon environmental

antigens.

FEATURES OF ALLERGIC DISEASES :

Allergens

- refers to an antigen that triggers an Ig E response in genetically

predisposed individuals.

Type 2 Helper T cells

- Secrete cytokines favoring Ig and E synthesis and are involved

in host defense against extracellular organisms such as

parasites.

Eosinophils

- Allergic diseases are characterized by peripheral blood and

tissue eosinophilia.

- Contains intracellular granules that are sources of inflammatory

proteins.

Mast Cells

- Derived from CD 34 hematopoietic progenitor cells that arise

from the bone marrow.

- Contains histamine, serine proteases and proteoglycans.

Note:

• The most important mass cell-derived lipid mediators are the

cyclo-oxigenase and lipoxygenase metabolites of Arachidonic

Acid.

• The major Cyclo-oxygenase product of mass cells is

Prostaglandin D2.

• The major lypoxygenase products are the

sulfidopeptideleukotrienes : LTC4 and its peptidodytic

derivatives LTD4 and LTE4.

MECHANISMS OF ALLERGIC TISSUE INFLAMMATION

Classification of Ig E – mediated immune responses:

1. Early phase response.

2. Late phase response.

3. Chronic Allergy diseases.

Early Phase Response

- Immediate response after introduction of allergen into target

organs.

- Within 10 minutes after allergen exposure and resolving within

1-3 hrs.

- e.g. leakage of plasma proteins tissue swelling increased blood

flow.

- Ex. Itching, sneezing, wheezing, acute abdominal cramps in the

skin, nose, lung, and GIT.

Late Phase Response

- Can occur within hrs of allergen, exposure, reaching a

maximum at 6-12 hrs and resolving by 24 hrs.

Clinically – cutaneous LPRs

- Characterized by edema, redness, and induration; sustained

nasal blockage, wheezing.

Chronic Allergic disease

- Tissue inflammation can persist for days to years.

- Risk Factors: recurrent exposure to the allergens and microbial

agents.

- Ex. Asthma – remodeling involves thickening of the airway.

Atopic dermatitis – lichenification

DIAGNOSIS OF ALLERGIC DISEASE

• Allergy History

• Risk of allergic disease in a child whose parent is allergic-50%

• Both parents 66%

CHARACTERISTIC BEHAVIOR OFTEN SEEN IN ALLERGIC CHILDREN :

Allergic Salute

- rubbing their nose upward with the palm of their hand because

of the nasal pruritus and rhinorrhea .

Nasal Crease

- a horizontal skin fold over the bridge of the nose.

Allergic Cluck

- is produced when the tongue is place the roof of the mouth to

the form to form a seal and withdraw rapidly in an effort to

scratch the palate.

Aeroallergens

- pollens or fungal spores are prominent causes of allergic

disease whose concentration in outdoor air fluctuates

seasonally.

PHYSICAL EXAMINATION

Allergic shiners

- blue gray to the purple discoloration beneath the lower eyelids

attributed to venous stasis.

Dennie lines

- Prominent symmetric skin folds that extent in an arc from the

inner canthus beneath and parallel to the lower lid margin.

Conjuctival Injection and edema

- in allergic conjunctivitis

External Ear

- eczematoid changes in Atopic Dermatitis.

Nasal Patency

- should be assessed, examine for septal deviation, turbinate

hypertrophy, septal spurs, or nasal polyps.

Pale to purple nasal mucosa

- suggest allergic rhinitis.

Lips

- Reveal cheilitis cause by drying of the lips from continuous

mouth breathing and repeated licking of the lips

Post pharynx

- Presence of post nasal drip and post pharyngeal lymphoid

hyperplasia.

Xerosis

- Dry skin in the most common skin abnormality of allergic

children.

Keratosis Pilaris

- Found on the extensor surfaces of the upper arms and tight,

characterized by roughness of the skin caused by keratin plugs

logged in the openings of hair follicles.

Atopic Dermatitis

- A chronic, heritable, cutaneous inflammatory disease

characterize by early age of onset of intense pruritus.

- Skin lesions maybe dry, easily irritated, weeping

Atopic Dermatitis

- Atopic Eczema

- Genetic predisposition

- Relapsing course

- Increase serum Ig E

CLINICAL MANIFESTATIONS :2 STAGES

I. Infantile stage

- begins during the 4th-6th months

- Erythematous, pruritic, weeping dermatitis in the cheeks which

spread to the forehead and extensor surface of the arms and

legs.

- Cradle cap

- Disappears between 3rd – 5thyear of life.

II. Childhood stage

- May disappear before 10 years of age or continue to adulthood.

- “Mark of atopic dermatitis” where there is whitish hue of the

face.

Stigmas of atopic dermatitis pruritus

- Characterized all phases of atopic dermatitis, intense during

infancy.

Lichenification

- A dramatic increase in the visibility of the normal geometric

skin markings pruritic on the sides of the neck and in the

popliteal and antecubital fossa.

Dennie’s line

- A prominent fold on the lower eyelid

Atopic palms

- Increase fine palmar and digital creases and lines which are

presumed to be a manifestation of dry skin.

Buffed Nails

- produced by chronic scratching and rubbing

Abnormal Vascular reactions

- Studying of the skin of AD patient produces an initial

erythematous line that is quickly replace by whitish blanch –

“white demographism”

Dryness xerosis

- Seen on the extensor surface of the extremities where there is

also keratosis pilaris

- Deficient sweating

Atopic Personality

- Reactive , active aggressive and somewhat hostile

Atopic foot

- erythematous scaling eczema involving dorsal and ventral

Aspect of the big toes

TREATMENT:

• Avoidance of the triggers

• Food allergens: peanut, milk, eggs, and seafood, inhalants

(houses dust mites , mold spores)

• Extreme change of temperature

• Good hydration - bathing or soaking the affected area for 15

mins in tepid water

• Use of oatmeal to the bath water for soothing

• Moisturizer / Creams

• Avoid soap and detergents, wool, silk, nylon, and other

synthetic fabrics- physical irritants.

ASTHMA

- A chronic inflammatory disorder of the airways in which cell

play a role, including mast cells and eosinophils.

- Etiopathogenesis:

• Hyperresponsive of the airway muscles Activated by:

autonomic

• Immunologic

• Infectious- Viral agents

• Endocrine

• Physiologic

- VIP (vasoactive Intestinal peptide)

Smooth muscle relaxation

- Local hormonal factors (histamine and leukotriene)

produces bronchoconstriction

Increase IgE

- Endocrine Factors

• worsens asthma during pregnancy menstruation and

onset of menopause

• At puberty – improves Thyrotoxicosis worsens the

severity of asthma

- Emotional factors

• Abnormal behavioral characters- affects child’s self

confidence

- Pathophysiology

Triad:

Smooth muscle spasm with hypertrophy

Mucosal edema

Plugging with tenacious albumin, epithelial cells

and eosinophilic leukocytes

- Lung Hyperinflation:

• Increase Residual Vol. and FRC

• Decrease VC, IC-ERC

• Decrease Lung compliance

• Ventilation- perfusion mismatch

- Clinical Presentation

• Wheezing ( High pitched or squeaking expiatory

sound)

• Cough- prolonged expiatory phase

• Tachypnea and dyspnea with used of accessory

muscles of respiration

• Hyperinflation of the chest

• Tachycardia

• Abdominal pain with vomiting

• Excessive sweating

• Fatigue and low grade fever from increase work of

breathing

• Hunched-over sitting position

- Laboratory

• Chest X-Ray – Hyperinflation with peribronchial

thickening

- Allergy skin test or RAST

“not all that wheezes is asthma”

- DDx:

• Congenital malformations of the respiratory tract

• Cardiovascular and GI systems, FB, Croup,

bronchiototis, endobronchial TB, etc.

- Children over 5y/o

o Spirometry

o Peak flow measurements

- Management:

1. Bronchodilator – β2 agonists, theophylline, anticholinergic

(ipatropium bromide)

2. Anti-inflamatory Agents – nedocromil sodium, sodium

cromoglycate, costicosteroids)

STATUS ASTHMATICUS

- severe acute asthma

- progression of the attack unresponsive to the usual appropriate

therapy

- Characteristics:

1. Hx of frequent repeated attacks, excessive daily use of

bronchodilator, corticosteroids

2. Use of accessory muscles

3. Pulses paradoxus

4. Change in consciousness

5. Cyanosis

6. Pneumothorax and pneumonediastinum

7. Hypoxemia with a paCO2 less than 60mmHg

8. Hypercapnea

9. Metabolic acidosis

10. FEV1 less than 20% predicted value

11. EKG abnormalities like p PulmonaleR vent. R Strain,

bundle branch blocks, R axis deviation

- Adverse Drug Reaction

• Type I – Drug Reaction

Urticaria , pruritus, Ig E

• Type II – Cytotoxic Reactions

The antigenic determinants of the drug will

interact with Ig G or Ig M or both antibodies will

bind with the lymphocyte, leukocyte a platelets of

the drug sensitive patients.

Activation is the destruction of the target cells

Ex. Quinidine – induced hemolytic anemia

• Type II – toxic complex syndrome or Arthus phenomenon

prototype of serum sickness

Symptoms are due to tissue damage brought

about by the action of proteolytic enzymes

liberated from neutrophils.

Clinical Features : Urticaria with or without

angioedema erythmatous, maculopapular

rashes, erythema multiforme, arthralgia

• Type IV-V- cell – mediated

Allergic reaction involves the lymphoid cells and

not the hormonal antibodies

Prototype: contact dermatitis (drug induced) –

reaction to topical creams and lotion

ATOPIC DERMATITIS

- Definition

• Atopic Dermatitis – eczema- itchy skin

• Greek – meaning

o (cc-) over

o (-ze) out

o (-ma) boiling

- Infants &small children (affects 1 in 7)

- Atopic dermatitis of childhood may reappear at different site

later in life.

- Cause :

• Inborn skin defects that tends to run in families, e.g.

asthma or hay fever

• 85% with high serum IgE and + skin tests food &

inhalant

- Distribution:

• In infants , the face is often affected first, then the

hands and feet; dry red patches may appear all over

the body

• In older children , the skin folds are most often

affected, especially the elbow creases and behind the

knees.

• In adults , the face and hands are more likely to be

involved.

- Associated features

• the skin is usually dry, itchy & easily irritated by:

- soap

- detergents

- wool clothing

• May worsen in hot weather & emotional stress.

• May worsen with exposure to dust and cats.

- Associated findings:

• Xerosis

• Keratosis Pilaris

• Itchythyosis

• Hyperlinear Palmar Creases

- Diagnosis:

• Major Characteristics

o Pruritus with or without excoriation

o Typical morphology and distribution

o Chronic relapsing dermatitis

o Personal or family history of atopy (asthma,

allergy, atopic derm, contact urticaria)

• Other characteristics

o Xerosis/Itchythysis/palmarhyper/kerat. pilaris

o Early age of onset

o Cutaneous colonization and/or overt infections

o Hand/foot/nipple/contact dermatitis, cheilitis,

conjunctivitis, erythroderma, subcapsular

cataracts

- Differential Diagnosis

• Seborrheic dermatitis

• Drugs

• Scabies

• Drugs

• Psoriasis

• Allergic contact dermatitis

• Cutaneous T-cell lymphoma

- Treatment:

1. reduces contact with irritants (soap substitutes)

2. reduce exposure to allergens

3. emollients

4. topical steroids

5. antihistamines

6. antibiotics

7. Steroid sparing

8. other (herbals, soaps)

- Reduce contact with irritants

• avoid overheating lukewarm, baths, 100% cotton

clothes, & keep bedding to minimum

• Avoid direct skin contact with rough fibers,

particularly wool, & limit/eliminate detergents

• Avoid dusty conditions & low humidity

• Avoid cosmetics (make-ups, perfumes) as all can

irritate

• Avoid soap-use soap substitute

• Use gloves to handle chemicals and detergents

- Soap Substitute

• Cetaphil-soap substitute – far less drying and irritating

than soap

• Cleansing & moisturizing formulations, all OTC

• Lotion, bar, soap, cream, sunscreen

• Costs about $8-9 for 16oz

- Reduce Exposure to allergens

• Keep home, especially bedroom, free of dust

• Allergic reactions module house dust mute, molds,

grass pollens & animal dander

• Special diets will not help most individuals b/c little

evidence that food is major culprit

• If food allergies exists, most likely d/t dairy products,

eggs, wheat, nuts, shellfish, certain fruits of food

additives

- Emollients

• Emollients soften the skin soft and reduce itching

• Moisture Trapping effective4s

o Best: Oils (e.g. Petroleum Jelly)

o Moderate creams

o Least Lotions

• Apply emollients after bat5hing and times when the

skin is usually dry (e.g winter months)

• Large variety (e.g. Vanicream, Eucerin, Luubriderm,

moistured, curel, neutrogerm)

• Inexpensive emollients include vegetable shortening

(Snowdrift by Martin White) and petroleum jelly

(Vaseline)

• Urea Creams

• Oils

- Emollients: Alpha – Hydroxy acid

• Creams are excellent for relieving dryness, but can

sting & sometimes aggravate eczema

• Useful for maintenance when no longer inflamed

• Forces epidermal cells to produce keratin that is

softer more flexible and less likely to crack

• Preparations

o Glycelic Acid (8%)

o Lactic Acid or Lac-Hydrin (5-12%)

o Urea (3-6%)

• Use IX/day

- Emollients: Oils

• Consider using bath oil or mineral oil-based lotions in

lukewarm bath water

• Add to tub 15 minutes into bath

• Bath oil preparation

o Alpha-keri

o Aveeno bath

o Jeri-bath

• Colloidal oatmeal (Aveeno) reduces itching

- Corticosteroids

• Topical steroids very effective

• Ointments for dry or lichenified skin

• Creams for weeping skin body folds

• Lotions or scalp applications

• Hydrocortisone 1-2.5%appliead to all skin

• Quite safe used even for months

• Use intermittently thin areas-(e.g.-face & genitals)

• Stronger potency topical steroids for non-facial

genital regions.

• Avoid potent ultra potent topical steroid preparations

on face, armpits, grains & bottom

• Once under control, intermittent use of topical

corticosteroid may prevent relapse

• Systemic ateroids may bring under rapid control, but

may precipitate rebound

• Once daily probably most cost effective

- Steroids and Young children

• Fluticasongproprionate cream 0.05%

• Moderate – severe atopic derm>3months

• Applied bid 3-4 weeks –mean 64% BSA

• No HPA suppression

- Corticosteroids: Pearls

• Different preparations prescribed for different parts

of the body for different situations

• Educate on

o Potencies & proper usage

o Write down directions

• Bring all topicals each appointment to clarify use