Causes of pityriasis rosea

By Dr Ananya Mandal, MD

Pityriasis rosea is a common skin condition that affects 0.15% of the general population. The condition often occurs in older children and young adults between ages 10 and 40 years and is rare among elderly and infants.

The condition has been described for more than two centuries and has a characteristic rash that begins with a small patch called the “herald patch”. This is followed by spread of a red, scaly, itchy rash to the chest, back, arms and legs. Women are at a slightly higher risk of this condition. 1-7

Is pityriasis rosea an infection?

The exact cause of this condition is still unknown. There are certain factors that lead to the belief that this may be caused by a viral infection.

The reasons for this belief is that pityriasis rosea tends to occurs in epidemics and affects large groups of persons together in a community especially during spring and autumn seasons. This could mean an infectious agent is responsible for the condition. In addition, recurrence is rare and this means that persons getting the rash may develop long lasting immunity to the infectious agent responsible for the condition.

Another significant sign that there could be an infectious agent behind pityriasis rosea is that more than 50% of the patients have some symptoms of feeling unwell before the appearance of the herald patch. This precedence of rash with general feeling of being unwell (termed prodromal symptoms) is common in cases of other viral infections. The course of the disease is also well defined and similar for most affected persons and follows a pattern much like other viral infections like measles or chicken pox.

In addition, some patients also show an increase in B lymphocytes and a decrease in T lymphocytes along with increase in Erythrocyte sedimentation rate (ESR). Lymphocytes are white blood cells that fight against infections so their rise is also significant. In addition, many infections show a rise in the ESR.

What may be causing pityriasis rosea?

Some studies have suggested that a virus may be causing pityriasis rosea. When seen under an electron microscope viral changes and virus particles have been noticed. However ,blood tests for antibodies against the viruses or special tests like polymerase chain reaction for viruses have not been positive to pinpoint a specific virus causing the condition.

Some studies have implicated Human Herpes Virus 6 and 7 in causation of pityriasis rosea. Other infections that need to be considered as causative agents of this condition include Legionella pneumoniae, Chlamydia pneumoniae and Mycoplasma pneumonia. However, these have not been proved.

Studies have suggested that some drugs may lead to drug-induced pityriasis rosea. These include:

  • barbiturates (sedatives)
  • bismuth
  • captopril (used in high blood pressure)
  • gold (used in rheumatoid arthritis)
  • metronidazole (antibiotic)
  • D-penicillamine (chelating agent used in certain poisonings)
  • isotretinoin (anti-aging skin preparation)

Despite these speculations, and occurrence of the rash in more than one person in a household at a time and more than one person in the community at a time, the disease is not contagious and does not spread from one person to another by touching.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Feb 8, 2014

Read in | English | Español | Français | Deutsch | Português | Italiano | 日本語 | 한국어 | 简体中文 | 繁體中文 | Nederlands | Русский | Svenska | Polski
Comments
  1. Viviane Basílio Viviane Basílio Brazil says:

    Tive na gravidez, isso pode trazer algum problema de pele pro futuro do meu filho?

  2. Tiny Tonka Tiny Tonka United States says:

    I have had this condition for many years now and I believe it might be genetic. My case of PR behaves contrary to everything described above as being characteristic of a virus.  I get outbreaks frequently (even though I am not immunocompromised as far as I know), and my first episode lasted for upwards of 6 months, and began creeping towards my face near the end (which it supposedly does only in rare cases).  I use a special soap to keep it at bay and I haven't passed it along to anyone else, including anyone I've shared a bed with. My PR did not show up until my mid/late 20s and, with my most recent episode, my mom told me, "Oh! I used to get that all the time when I was younger." My episodes are not very painful either and only itch mildly and intermittently. The worst itch was with the first herald patch. With recurrences, I don't even get a herald patch anymore.

  3. J P J P United States says:

    My first experience with PR ever. My dermatologist says she even got it, while in England, prior to being a derma-student. My family has very little medical history, if at all, apart from few high blood pressure persons. I've been caring for a lot of Mycoplasma patients this winter season and singled out either this (droplet isolation) or my contact isolation patients, which may have induced my skin reaction...I'm thinking it is more to do with a droplet source though since gloves are better barriers than a flimsy mask. I noticed it around Jan. 5; it is now Feb. 8 and minor, non-itchy patches are still sprouting then enlarging.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
Post a new comment
Post