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Diseases and Conditions
Pityriasis rosea
From MayoClinic.com
Special to CNN.com

Introduction

Pityriasis rosea is a common skin condition in children and young adults. It usually begins as one large spot on your chest, abdomen or back and then spreads. The rash of pityriasis rosea often sweeps out from the middle of the body, and its shape resembles drooping pine-tree branches.

Although pityriasis rosea has a distinctive appearance once the rash appears, in its early stages you may confuse pityriasis rosea with other skin disorders, such as ringworm or eczema.

The cause of pityriasis rosea is unclear, but it may be the result of a virus. Pityriasis rosea usually goes away on its own within six to eight weeks. In the meantime, you can take steps to relieve the discomfort.

Signs and symptoms

Characteristics of pityriasis rosea include:

  • Initial phase. Pityriasis rosea typically begins with a large, slightly raised, scaly patch — called the herald patch — on your back, chest or abdomen.
  • Progression. Smaller fine, scaly spots usually appear across your back, chest or abdomen in a pine-tree pattern a few days to a few weeks after the herald patch. Rarely, smaller spots may also appear on your arms, legs or face. The rash may itch.
  • Color. The rash of pityriasis rosea often is scaly and pink, but if you have darker skin, it may be gray, dark brown or even black.
  • Other signs and symptoms. About half the people who develop pityriasis rosea have signs or symptoms of an upper respiratory infection — such as a stuffy nose, sore throat, cough or congestion — just before the herald patch appears.

Causes

The exact cause of pityriasis rosea is unclear, although the cause may be a viral infection, such as certain strains of the human herpes virus (HHV6 or HHV7).

When to seek medical advice

See your doctor if you develop any of the following signs:

  • A large scaly patch on your back, chest or abdomen
  • A rash across your back, chest or abdomen
  • A rash on your arms, legs or face

Also contact your doctor if you've been diagnosed with pityriasis rosea, and the rash doesn't go away within three months.

Complications

Pityriasis rosea can cause severe itching, especially if you become overheated.

The rash usually fades without leaving any permanent marks. But, if you have dark skin, long-lasting flat, brown spots may remain after the rash has healed.

Screening and diagnosis

If your doctor suspects you have pityriasis rosea, he or she will do a physical exam, inspecting the spots that have appeared on your skin. Often, this exam is all it takes to diagnose pityriasis rosea.

In its early stage, however, pityriasis rosea can look like several other skin diseases, including ringworm, eczema, psoriasis or secondary syphilis. Your doctor may order blood tests or a skin biopsy to rule out these conditions.

Treatment

In most cases, pityriasis rosea goes away in four to eight weeks. Treatment usually focuses on controlling itching. The antiviral drugs acyclovir and famciclovir and the antibiotic erythromycin may reduce the duration of pityriasis rosea to one to two weeks. These medications often are not necessary, however, because itching is usually mild, and the condition clears up on its own.

If itching is a problem, your doctor may recommend the following to provide relief:

  • Steroid creams or ointments. These creams will help ease itching and decrease redness.
  • Oral antihistamines. These medications are available by prescription as cetirizine (Zyrtec) and fexofenadine (Allegra), and over-the-counter as diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), clemastine (Tavist) and loratadine (Claritin).
  • Light therapy (phototherapy). This can be with ultraviolet B (UVB) light or sunlight. Talk to your doctor before using sunlight to treat your rash. UVB therapy is most often available at your doctor's office.

Self-care

These steps may help relieve the discomfort of pityriasis rosea:

  • Bathe and shower in lukewarm water.
  • Take an oatmeal bath. You can find oatmeal bath products at your pharmacy.
  • Use zinc oxide cream or calamine lotion on the rash.
  • Avoid strenuous physical activity if sweating makes the itching worse.

April 03, 2006

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