Pityriasis rosea a generalised, self limiting rash that has an unknown cause. It often occurs in adolescents and young adults. It may be caused by a virus such as human herpes virus (HHV-6 or HHV-7), but no definitive causative organism had been established.
There may be prodromal symptoms prior to the rash developing. These include headache, tiredness, loss of appetite and flu-like symptoms.
The rash starts with a characteristic herald patch. This is a faint red or pink, scaly, oval shaped lesion that is 2cm or more in diameter, usually occurring somewhere on the torso. It appears 2 or more days prior to the rest of the rash. If you suspect pityriasis, ask and look for a herald patch. Most, but not all, patients have a herald patch.
The rash consists of widespread faint red or pink, slightly scaly, oval shaped lesions, usually less than 2 cm in diameter. On the torso they can be arranged in a characteristic “christmas tree” fashion, following the lines of the ribs.
In dark skinned patients the lesions can be grey coloured, lighter or darker than their skin colour.
Other symptoms may be present:
- Generalised itch
- Low grade pyrexia
The rash resolves without treatment within 3 months. It can leave a discolouration of the skin where the lesions were, however these will also resolved within another few months.
There is no treatment for the rash. It will resolve spontaneously without any long term effects. Patient education and reassurance is all that is required. It is not contagious and they can continue all their normal activities.
They may require symptomatic treatment if bothered by itching. This may include emollients, topical steroids or sedating antihistamines at night to help with sleep (e.g. chlorphenamine).
Last updated January 2020