Notes and photos from dermnet – https://www.dermnetnz.org/topics/pityriasis-rosea/
 
effects young adults – 15 – 30 years of age 
 

Systemic symptoms

Many people with pityriasis rosea have no other symptoms, but the rash sometimes follows a few days after a upper respiratory viral infection (cough, cold, sore throat or similar).

What causes pityriasis rosea?

Pityriasis rosea is associated with reactivation of herpes viruses 6 and 7, which cause the primary rash roseola in infants. Influenza viruses and vaccines have triggered pityriasis rosea in some cases.
 
FIRST – 
i single rash comes first – ( called a herald patch) 
Herald = a sign that something is about to happen 
this herald patch can be oval/round shaped – ( some times can have 1-2) 
hence this is mostly mistaken for a ring worm – and discoid eczema 
 
in about 1-2 weeks – a generalised rash erupts – 
they are coin shaped , salmon pink / copper colour – with a scaly margin ( .5-2 cm in size /smaller than the hareld patch) – and the scales are in the inside of the active edge , and has a central clearance 
The rash comes along the cleavage lines  (Langers lines) – giving the appearance of a Christmas tree.
 
Distributed mainly in trunk -with a few rashes on upper thigh and upper arms 
uncommon on the face or scalp
Itchiness can be 0 / no – to severe 
most cases dont itch 
 
 
 
DIAGNOSIS – 
Essential clinical features
Discrete circular or oval lesions
Scaling on most lesions
Peripheral collarette scaling with central clearance on >2 lesions
Optional clinical features
At least one of the following features should be present:
Truncal and proximal limb distribution (<10% of lesions distal to mid-upper-arm and mid-thigh)
Most lesions along skin cleavage lines
Herald patch ≥2 days before other lesions
 
 
Differential diagnosis
Herald patch: tinea corporis/discoid eczema.
Generalised rash: seborrhoeic dermatitis (slower onset), guttate psoriasis, drug eruption (see Table 124.3), secondary syphilis.
 
Prognosis
A mild, self-limiting disorder with spontaneous remission in 2–10 weeks (average 2–5). It does not appear to be contagious. Recurrence is rare.
Management  – 
  1. reassure
  2. based on itchiness steroid creams
  • mild – apply mild topical corticosteroid ointment or calamine lotion with 1% phenol or menthol 1% in aqueous cream.
  • severe – use a potent topical corticosteroid once or twice daily or oral corticosteroids.
  1. UV therapy is good but, like psoriasis, sunburn must be avoided. Expose the rash to sunlight or UV therapy (if florid) three times a week, with care.
  2. Expose skin to sunlight cautiously (without burning). – this would help for it to resolve 
  3. Bathe and shower as usual, using a neutral soap (e.g. Neutrogena).
  4. Use a soothing bath oil (e.g. QV Bath Oil).
Extracted from eTG
 
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