Lec 4: Eczema

Question 1

Eczema Causes

Answer 1

intense itchiness > scratching.

Question 2

Dermatitis

Answer 2

skin inflammation (broader term than eczema)

Question 3

Eczema histology

Answer 3

Acute
Chronic

Question 4

Acute Stage eczema

Answer 4

1. Epidermis oedema > spongiosis.
2. Intra-epidermal vesicles
3. Vesicles coalesce into larger blisters or rupture.
4. Plasma weeping.
5. Crusting

Question 5

Chronic Stage Eczema

Answer 5

1. Less spongiosis & vesication.
2. Prickle (acanthosis) & horny layer (hyperkeratosis & parakeratosis) thickening.
3. Variable degree of vasodilatation and infiltration with lymphocytes.
4. Scales, fissures, lichenification appear.

Question 6

Eczema Pathogenesis

Answer 6

Hallmark > inflammation & activated keratinocytes

Question 7

Eczema TSAD

Answer 7

T: plaques.
S: red, scaly, ill-defined.
A: not specific.
D: asymmetrical, on wrists & flexures.

Question 8

Eczema Complications

Answer 8

• 2ry bacterial infection > recurrent impetigo.
• Itchy sleepless child > wreck family life.
• Can interfere with work, sporting activities, sex lives, and job.

Question 9

Eczema Investigations

Answer 9

Biopsy > confirmatory.

Question 10

Irritant Contact Dermatitis (ICD) epidemiology

Answer 10

80% of dermatitis cases
Common in children.

Question 11

ICD Etiology

Answer 11

• Brief contact with strong irritants.
• Prolonged contact with weak irritants.
• People with very dry skin.
• Past or present atopic dermatitis increase the risk.

Question 12

ICD Distribution

Answer 12

Hands & forearms.

Question 13

ICD Common irritants:

Answer 13

Water, detergents, chemicals, solvents, cutting oil & abrasive dusts.

Question 14

ICD Course

Answer 14

• The need to continue at work, often stops the skin regaining its normal barrier function.
• Even under ideal circumstances, it may take several months.
• Probably reversible in the early stages.
• In most cases, it becomes chronic.

Question 15

ICD Complications

Answer 15

May lead to loss of work.

Question 16

ICD Differential Diagnosis:

Answer 16

Allergic contact dermatitis.
Atopic eczema.

Question 17

Is patch test helpful in ICD?

Answer 17

No :)

Question 18

Treatment of ICD?

Answer 18

• Avoidance of the irritants
• Moderately potent topical CS & emollients

Question 19

Allergic Contact Dermatitis (ACD) etiology

Answer 19

Delayed hypersensitivity (type IV).

Question 20

Allergic Contact Dermatitis (ACD) Criteria

Answer 20

• There must be a previous contact to induce the allergy > contact or ingestion (nickel (present in plants)).
• Specific to 1 chemical & its close relatives.
• After allergy has been established, all areas of skin will react to the allergen.
• Sensitization persists indefinitely
• Desensitization rarely possible

Question 21

Allergic Contact Dermatitis (ACD) Suspected if:

Answer 21

• If certain areas are involved (eyelids, external auditory meati, hands, feet, and around gravitational ulcers).
• There is a known contact with the allergens.
• Individual’s work carries a high risk. (ACT is especially common in metal workers, hairdressers, healthcare workers, cleaners, painters and florists)
• Patients with atopic dermatitis associated with defective Filaggrin (structural protein in the stratum corneum) have a high risk of also developing ACT.
• For some substances 1 exposure is enough for sensitization & other need prolonged exposure.
• It is more common in female more than male, due to nickel allergy (earring and jewelry) and recently from acrylate allergy associated in nail cosmetics.
• Many young children are also allergic to nickel.
• It is specific to one chemical and its close relatives.
• After allergy has been established, all areas of skin will react to the allergen.

Question 22

Allergic Contact Dermatitis (ACD) Pathogenesis

Answer 22

• The T cells that are involved are memory cells derived from prior stimulation of same antigen.
• The mechanism involves CD4+T lymphocytes which recognizes an antigen on skin surfaces, releasing cytokines that activate the immune system.

Question 23

Presentation of ACD

Answer 23

Affected skin may be:
- Red and itchy.
- Swollen and Blistered.
- Dry and bumpy.

Question 24

ACD Investigations

Answer 24

Patch testing > gold standard.
- Done on back.
- Detect type IV hypersensitivity.

Question 25

ACD treatment

Answer 25

Avoidance
Job changes
Topical CS