Bruce P.Robinson, MD
Pityriasis Rosea is a rash that occurs most commonly in people between the ages of 10 and 35, but may occur at any age. The rash can last from several weeks to several months. Usually there are no permanent marks as a result of this condition, although some darker-skinned persons may develop long-lasting flat brown spots that eventually fade. It may occur at anytime of year, but Pityriasis Rosea is most common in the spring and fall.
Pityriasis rosea usually begins with a large, scaly, pink patch on the chest or back, which is called a herold or mother patch. It is frequently confused with ringworm, but antifungal creams do not help because it is not a fungus.
Within a week or two, more pink patches appear on the chest, back, arms, and legs. Patches may also occur on the neck, but rarely on the face. The patches are oval and may form a pattern over the back that resembles the outline of a Christmas tree. Sometimes the disease can produce a very severe and widespread skin eruption. About half the patients will have some itching, especially when they become warm. Physical activities like jogging and running, or bathing in hot water, may cause the rash to temporarily worsen or become more obvious. There may be other symptoms including fatigue and aching. The rash usually fades and disappears within six to eight weeks, but can sometimes last much longer.
The cause is unknown. Pityriasis Rosea is not a sign of any internal disease, nor is it caused by a fungus, a bacteria, or an allergy. There is recent evidence suggesting that it may be caused by a virus since the rash resembles certain viral illnesses, and occasionally a person feels slightly ill for a short while just before the rash appears. However, this has not been proven. Pityriasis rosea does not seem to spread from person to person and it usually occurs only once in a lifetime.
Pityriasis rosea affects the back, neck, chest, abdomen, upper arms, and legs, but the rash may differ from person to person making the diagnosis more difficult. The numbers and sizes of the spots can also vary, and occasionally the rash can be found in an unusual location such as the lower body, or on the face. This usually occurs in older individuals. Fungal infections, like ringworm, may resemble this rash. Reactions to certain medications, such as antibiotics, water pill, and heart medications can also look the same as Pityriasis Rosea.
The dermatologist may order blood tests, scrape the skin, or take a sample from one of the spots (skin biopsy), to examine under a microscope in order to make the diagnosis.
Pityriasis rosea often requires no treatment and it usually goes away by itself. However, treatment may include external or internal medications for itching and soothing medicated lotions and lubricants may be prescribed. Lukewarm rather than hot baths may be suggested. Ultraviolet light treatments given under the supervision of a dermatologist may be helpful.
Occasionally, anti-inflammatory medications such as corticosteroid may be necessary to stop itching or make the rash go away. Patients should be reassured that this disease is not a dangerous skin condition even if it occurs during pregnancy.
Remember that Pityriasis Rosea is a common skin disorder and is usually mild. Most cases usually do not need treatment and fortunately, even the most severe cases eventually go away.
