Pityriasis rosea

Question 1

Define pityriasis rosea

Answer 1

Self-limiting skin rash that mainly affects young adults — it is characterized by distinctive, scaly, erythematous lesions and, in some people, a herald patch that typically appears 5–15 days before the more generalized rash.

Question 2

Symptoms and signs of pityriasis rosea

Answer 2

Starts with herald patch
- 5-15 days between
- Larger 2-5cm diameter patch
- Well defined, round erythematous and slightly raised rash
Rash
- Multiple, discrete, pink-red “salmon pink”/fawn coloured
- Flat/slightly raised
- Circular/oval 0.5-1cm in diameter
- Slightly scaly
- Collarette scaling due to central clearing
- Mostly on trunk and proximal limbs, NOT on palmar/plantar surfaces
- - Trunk: along the lines of cleavage parallel to the ribs → Christmas tree pattern on back, V shape on chest

Question 3

Differentials for pityriasis rosea

Answer 3

Guttate psoriasis: tear drop scaly papules, preceded by strep throat
Discoid eczema
Drug reaction
HIV seroconversion
Lichen planus
Pityriasis versicolor

Question 4

Management for pityriasis rosea

Answer 4

None required
Resolves within 2-3 months
May worsen before resolving, new lesions arise for up to 6 weeks
After the rash has disappeared, there may be some hyperpigmentation or hypopigmentation of the affected skin for several months, but there will be no scarring.
The rash does not usually recur: about 1 in every 50 people with pityriasis rosea may have a recurrence.

Itch:
- Emollient
- Topical steroid e.g. hydrocortisone 1% (CI if severe)
- Oral antihistamine e.g. chlorphenamine

Pregnancy → discuss urgently with obs

Question 5

Prognosis for pityriasis rosea

Answer 5

Resolves spontaneously within 2-12 weeks
Can take up to 5 months to disappear
New lesions may continue to appear in the first 2-6 weeks
There may be some temporary hyperpigmentation/hypopigmentation of the affected skin but NO scarring
Recurrence is 2-3%
After the rash has disappeared, there may be some hyperpigmentation or hypopigmentation of the affected skin for several months, but there will be no scarring.
The rash does not usually recur: about 1 in every 50 people with pityriasis rosea may have a recurrence.