Dermatitis

Question 1

What is the chemical in a lot of products that causes dermatitis?

Answer 1

methylisothiazolinone

Question 2

Causes of endogenous vs Exogenous dermatitis

Answer 2

Exogenous dermatitis 
  Irritant 
  Phototoxic 
Endogenous dermatitis 
  Atopic
  Discoid 
  Pityriasis alba 
  Lichen simplex 
  Seborrhoeic dermatitis 
  Vesicular 

Ref: Murtagh’s Page 1314

Question 3

What is Pityriasis alba?
Which age group does it affect?
Treatment?

Answer 3

1/ low-grade type of eczema/dermatitis that primarily affects children, triggered by exposure to sun
2/ 3-16 years
3/ usually improves without treatment

Question 4

What is seborrheic dermatitis?

Which skin commensal is it associated with?

Answer 4

Chronic form of dermatitis which affects the scalp and the face.

Can be associated with psoriasis.

Malasseizia

Question 5

Discoid dermatitis

Answer 5

Round oval plaque with well demarcated edges, intensely itchy, prone to bacterial infection.

Potent steroids e.g. betamethasone dipropionate 0.05% ointment topically, once daily for 2 weeks

Reference - etg

Question 6

Perioral dermatitis
1/ Triggers
2/ Treatment

Answer 6

1/ corticosteroid therapy, associated with OCP/pregancny, associated with seborrhoeic dermatitis on scalp and head, cosmetic products

2/ Cease all c/steroids, creams etc
Doxy 4-6 weeks 100mg daily
Topical metro or clinda

(murtagh’s, dermnet nz)

Question 7

DDx of atopic eczema?

Answer 7

Irritant dermatitis 
Discoid dermatitis 
Seborrhoeic dermatitis 
Pityriasis alba 
Psoriasis 
Scabies related itch 
Tinea related itch 

Other: cutaneous T cell lymphoma, autoimmune,

(dermnet nz, check may 2017)

Question 8

DDx of discoid eczema?

Answer 8

Neoplasm (Superficial BCC, Bowen’s disease)
I- Tinea
Autoimmune – Psoriasis
Dermatitis
Endogenous – discoid or nummular eczema, licehn simplex
Exogenous – atopic/irritant
Pityriasis roscea (herald plaque)

Question 9

Cradle cap.

Seborrhoic dermatitis

Answer 9

Will clear at 12-18 months of age