Presenting typically as a generalised body rash, the skin condition Pityriasis rosea is thought to be caused by a virus, although vitamin A deficiency has also been implicated. Increased incidence of the condition in the winter months suggests a viral aetiology. This is supported by the fact that patients often report a pre-history of upper respiratory tract infection.
The condition is quite common, particularly in people aged between one and 35, and females appear to be more susceptible than males.
The rash often starts with a 'herald patch', usually an oval-shaped patch, 2-5cm in diameter, which can occur on the chest, abdomen, neck, back, thighs or upper arms. The patch may be so innocuous as to not be observed, then about five to 15 days after its appearance a more widespread rash develops over a period of about ten days. It usually consists of oval, pink spots that are 1-3cm in diameter. These spots often seem to form in lines which follow the normal skin creases. Classically, the rash makes a Christmas tree pattern on the back or chest.
A Personal Experience
In the case of this Researcher, a man in his mid-50s, the herald patch appeared on the upper-left chest as a scaly, pink circle - 2cm in diameter - which resembled ringworm1. This patch remained for the duration of the condition. Following this, a bilateral rash developed on either side of the mid-abdomen. Some of this rash consisted of quite large, dark-pink, scaly circles with smaller bright-red spots in between. This rash morphology was not typical, resulting in the GP calling for the second opinion of a colleague. The actual diagnosis was made on the basis of the 'herald patch'. The main rash seemed to wax and wane from day to day, and sometimes could be more accurately described as weals. There were also bright-red itchy spots on the forearms, itchiness to the lower legs, and an eczemoid scaly rash on the upper left foot.
Medical texts say the rash can seem quite alarming, although, apart from experiencing a mild headache and general tiredness, sufferers do not usually feel unwell. The rash is said to fade with time and leave no lasting marks. The course of the condition may be quite long - up to two months - and, although seldom recurrent, second attacks have been reported2.
There is no treatment available which will clear the condition. Calamine lotion can be used to soothe the itchiness, however. If the itching is particularly troublesome, then a mild steroid cream such as hydrocortisone may be prescribed by your doctor.
As vitamin A deficiency has been implicated, it would be worthwhile checking that your diet contains foodstuffs that are rich in this vitamin, eg, carrots, dairy products such as butter and milk, and eggs.
A The Patient UK Experiences Discussion Group is available online, offering patients' experiences and advice on coping with Pityriasis rosea.