By Dr Ananya Mandal, MD
Ptyriasis rosea is a common skin condition and the symptoms often progress in three distinct stages. The first and second stages may be missed or may not occur in many patients.
The condition commonly affects older children and adults between ages 10 to 40 and peaks in age groups of 25 to 30. There is a slightly higher incidence among women but the reasons for this are unclear.
Elderly over eighty and young infants below 1 year of age are seldom affected. The exact cause of this condition is unclear but it is suspected that this may be caused by a viral infection. 1-7
Symptoms may be outlined according to the stage of the condition.
Prodromal (initial) symptoms of ptyriasis rosea
These occur in less than half of the affected individuals. These symptoms may last a week or so in these individuals. It includes:
Second stage symptoms of ptyriasis rosea
The second stage is the beginning of the rash stage. There is beginning of a red, oval patch of scaly skin that ranges from a size of 2 to 10 cm (0.8-4 inches) called the “herald patch”. This appears typically on the trunk over the abdomen or the chest.
The herald patch may also occur less commonly at other sites like genitals, scalp or face. The herald patch grows progressively over days.
Generalized skin rash
Thereafter a generalized skin rash appears. This usually takes a few days to two weeks from the first appearance of the herald patch.
These rashes are small, raised and red patches that are between 0.5 - 1.5cm in size. These appear over the chest, abdomen, arms, legs (thighs), neck etc. The face is usually unaffected.
The patches are commonly distributed in a ‘Christmas tree pattern’ on the upper back and a V shaped distribution over the chest. The rash extends as downward slanting triangular lines over the sides that give it an appearance of a Christmas tree or a fir tree.
In Caucasians and light skinned patients the rash appears pinkish or reddish in color. In dark skinned individuals these patches may appear grey, dark brown or black. The rash is usually not painful but in three fourths of all cases it may be itchy.
Itchiness may be mild in some but may range in severity and some people may develop severely itchy lesions. Itchiness worsens when the person is hot, sweating, wearing tight clothing or comes in contact with water.
Rarely some patients may develop plaques of patches and ulcers within their mouth. Both the herald patch as well as the secondary rash usually clears within three months or around 12 weeks. In some, the symptoms may persist for up to six months. Once the rash has healed there may be a darkening or lightening of the skin. This usually normalizes without treatment in a few months. There is no scarring with pityriasis rosea.
When to seek medical help
Medical help should be sought if the symptoms of itchiness are troublesome or if they are interfering with sleep or daily activities.
Medical help should be sought promptly if any of the following are the case:
those who have symptoms for over five months
those with rash that covers arms and legs but spares the trunk
those with a rash that is spreading rapidly over the body
the patches are leaking blood, clear fluid or pus
This is because these symptoms may indicate that this may be a different rash than pityriasis rosea.
Commonly skin conditions like psoriasis, sexually transmitted infection (STI) and skin manifestations of syphilis may need to be ruled out in these cases.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Sep 6, 2012