Eczema and dermatitis

Question 1

What is the histology seen in drug-related dermatitis?

Answer 1

Spongiotic rash and eosinophils

Question 2

What type of hypersensitivity reaction is involved in contact allergic dermatitis?

Answer 2

Type 4

Question 3

What is the immunopathology of contact allergic dermatitis?

Answer 3

Langerhans cells process antigen

This is then presented to the Th cells in the dermis

Sensitised Th cells migrate to lymphatics to amplify antigen presentation

Following this antigen challenge, specialised T cells proliferate and migrate to infiltrate skin

Question 4

Which dermatitis gets worse with every exposure to irritant/allergen: contact allergic dermatitis or contact irritant dermatitis?

Answer 4

Allergic

Question 5

What are the features of an eczema rash?

Answer 5

Itchy

Ill defined

Erythematous

Generalised dry skin

Flexural distribution

Question 6

What other conditions is eczema associated with?

Answer 6

Food allergy

Asthma

Allergic rhinitis

Question 7

What are some of the chronic changes that occur in atopic eczema?

Answer 7

Lichenification

Excoriation

Secondary infection

Question 8

What does secondary infection of eczema with crusting indicate?

Answer 8

Staph. aureus infection

Question 9

What does secondary infection of eczema with monomorphic, punched out lesions indicate?

Answer 9

Eczema herpeticum - infection with herpes simplex virus

Question 10

What are the diagnostic criteria for eczema?

Answer 10

Itching plus two or more of:

Visible flexural rash (cheeks and extensor surfaces in infants)
History of flexural rash

Personal history of atopy (or first degree relative if under 4 yo)
Generally dry skin
Onset before age 2 years

Question 11

How is atopic eczema treated?

Answer 11

Plenty of emollients

Avoid irritants including shower gels and soaps

Topical steroids

Treat infection

Phototherapy

Systemic immunosuppressants
Biologic agents

Question 12

What kind of phototherapy is used in eczema?

Answer 12

Mainly UVB

Question 13

What is the most important gene in eczema and what does it do?

Answer 13

Filaggrin

Filaggrin codes for filament aggregating protein – contracts all the keratin filaments and flattens them down, contributing to the skin barrier

Question 14

What rash is being shown here?

Answer 14

Stasis eczema

Question 15

What is stasis eczema secondary to?

Answer 15

Hydrostatic pressure
Oedema
Red cell extravasation

Question 16

What is the name given to the eczema that affects the hands and feet?

Answer 16

Pompholyx eczema

Question 17

What is the name given to the type of dermatitis that responds to trauma to skin i.e. from scratching?

Answer 17

Lichen simplex

Question 18

What kind of dermatitis is nappy rash?

Answer 18

Irritant contact