Pityriasis rosea is a common rash that usually begins with a rather large, often scaly patch, known as a herald patch, on the chest, back or abdomen. Although the rash spreads within hours or days of appearing, it is normally confined to the trunk of the body and the legs and does not affect the face, hands or feet. Most often, patients who develop this condition are between the ages of 10 and 35. The condition is not usually serious nor contagious and usually resolves on its own within 6 to 8 weeks.
Causes of Pityriasis Rosea
While the exact cause of pityriasis rosea is unknown, research demonstrates that it is not an allergic reaction and not bacterial or fungal in origin. It may be associated with certain viral infections since many patients experience mild viral symptoms, such as headache, fatigue, sore throat or nausea, prior to developing the rash.
Diagnosis of Pityriasis Rosea
Diagnosis of pityriasis rosea is usually made through an examination of the rash itself which sometimes takes the distinctive pattern of a Christmas tree. The rash is also noteworthy because of its absence from the face and hands. The color of the patches will depend on the color of the patient's normal skin tone and may vary from salmon to brown or gray. While about a quarter of the patients who have pityriasis rosea only experience the visible rash, the majority of patients are troubled by itching which for some may be severe.
Because the rash of pityriasis rosea may resemble rashes from other causes, the physician may take a recent medical history and administer blood tests or biopsies to rule out allergies, contact dermatitis, fungal infections, eczema or even syphilis. In some cases, blood tests or biopsies may be necessary.
Treatment of Pityriasis Rosea
Treatments for pityriasis rosea consist of the usual remedies for itching and rashes, such as colloidal oatmeal baths, steroid creams and antihistamines. Cool compresses, restricted use of soap or perfumed lotion, and the wearing of soft clothing may provide relief. Limited exposure to sun or phototherapy may also be helpful. If the symptoms of pityriasis rosea are particularly harsh, oral corticosteroids may be temporarily prescribed.
Complications of Pityriasis Rosea
Ordinarily, pityriasis rosea is not a dangerous condition and the rash leaves no residual damage, though if the patient develops a severe, pustular rash, there is potential danger of infection. Occasionally, patients are left with dark patches of skin but these normally disappear over time.
Pityriasis rosea can be serious when it occurs in pregnant women, particularly those in the early stages of pregnancy. There is evidence of a higher rate of miscarriage, premature birth and certain birth abnormalities in women who develop the disease at this time, possibly because a virus responsible for the rash damages the fetus. The risk appears to be greatest in women who have more extreme cases of the disorder.