Pityriasis rosea

Pityriasis rosea is a mild rash that causes scaly, rose-colored, inflamed skin lesions.


Causes/associated factors
The cause of pityriasis rosea is unknown, but it's thought to be related to a virus. Pityriasis rosea can develop at any age, but it typically affects people between ages 10 and 35. The condition affects females more often than males, and is most common in the spring and fall. Permanent scars or marks are uncommon, but some people may be left with areas that are lighter or darker than their normal skin color.

Transmission
The rash isn't contagious. Normally, you're not affected by pityriasis rosea more than once.

Signs/symptoms
An initial large pink or salmon-colored patch that feels rough or scaly usually develops on your trunk. This is often called the herald patch. A week or two later, you'll notice smaller patches on your arms, legs, and sometimes your neck or face. If you have darker skin, the patches may appear darker than your normal skin tone, rather than salmon-colored. The rash may follow the rib lines and form a pattern on your chest or back that looks like a pine tree with hanging branches. Less commonly, the rash will appear in the armpits, scalp, groin or penis. The spots may fade and reappear for weeks. Some people who develop this rash have mild to severe itching. Heat from exercise or bathing can make the rash look worse or reappear. The rash typically lasts from four to 16 weeks or possibly longer.
Pityriasis rosea may also produce prodromal symptoms. These are symptoms that develop either just before the initial patch or along with it. Prodromal symptoms may include sore throat, fatigue, joint pain, fever, nausea, headache or appetite loss.


Diagnosis
Pityriasis rosea can resemble rashes caused by reactions to medications or other diseases. Sometimes, the rash is mistaken for a fungal infection, such as ringworm. To make a diagnosis, the doctor will carefully examine your rash. Blood tests or skin scrapings can be used to rule out other possible causes of the rash. Your doctor may even choose to do a skin biopsy (taking a tissue sample for further analysis) if the diagnosis is uncertain.

Treatment
Pityriasis rosea typically clears up without treatment within several weeks to a few months. To relieve your itching, the doctor may recommend:
calamine lotion
zinc oxide
oral antihistamines (diphenhydramine or Benadryl, for example)
topical cortisone medications (applied directly to the skin)
ultraviolet light treatments (Natural sunlight may also relieve itching, but be careful to avoid sunburns.)
In severe cases, oral (taken by mouth) cortisone medications may be prescribed to relieve itching and inflammation.


Complications
Continually scratching the affected area can lead to a secondary bacterial infection of the skin. To help prevent infection, it's important to keep your skin clean and refrain from scratching. Scarring is possible if the rash becomes infected.

Pregnancy-specific information
Pregnancy doesn't increase the risk of developing pityriasis rosea. If you have pityriasis rosea during pregnancy, treatment measures may differ from those recommended for other adults.

Senior-specific information
Growing older isn't a risk factor for this pityriasis rosea.

Prevention
Researchers haven't identified a way to prevent pityriasis rosea.