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What Is Pityriasis Rosea?
Pityriasis rosea is a common and harmless rash that lasts about 6 to 8 weeks. It is usually found on the neck, torso, upper arms, or thighs.
What Are Symptoms of Pityriasis Rosea?
Pityriasis rosea symptoms evolve over a short time. The first symptom is often referred to as a “herald patch” or “mother patch,” which is a single red, scaly lesion. It may be slightly raised or rough in texture, is typically oval in shape, and measures from just under one inch to almost 4 inches in diameter. It usually appears on the back or chest first.
Following the appearance of the herald patch, within one to two weeks, more patches appear. These may be smaller and scaly and form on the chest or back. Itching is common.
Pityriasis rosea in individuals with brown or dark skin color (for example, people with African, Indian or Hispanic heritage) varies compared with those of Anglo heritage (pinkish coloration). Both the herald patch and the diffuse rash of the disease that occurs in people with brown or dark skin may develop either a gray, dark brown or black coloration.
In addition, after the lesions heal, there may be areas of hypopigmentation and/or hyperpigmentation (lighter or darker patches). These skin changes are sometimes difficult to identify and may lead to a delayed or misdiagnosis in some patients.
Some patients may have a “prodrome,” that is, symptoms that precede the herald patch. These early symptoms of pityriasis rosea include:
- Upper respiratory tract infection
- Loss of appetite
- Feeing unwell (malaise)
- Swollen lymph nodes
- Joint pain
What Causes Pityriasis Rosea?
The cause of pityriasis rosea is unknown. It is thought it may be caused by a virus. One theory is that it is a reactivation of herpes viruses 6 and 7, and another theory is that the influenza virus H1N1 is a possible cause.
Other experts have suggested a fungal infection is a more likely cause of pityriasis rosea than a viral infection, but this has not been proven.
Pityriasis rosea–like eruptions can also occur after taking certain drugs, such as:
- Acetylsalicylic acid
- Anti−tumor necrosis factor (TNF)-α agents
- Certain vaccines (e.g., bacille Calmette-Guérin [BCG], human papilloma virus, and diphtheria)
Drug-induced pityriasis rosea tends to last longer than non–drug-induced pityriasis rose.
Stress may also increase the occurrence of lesions.
How Is Pityriasis Rosea Diagnosed?
Pityriasis rosea can often be diagnosed by visual inspection of the rash and lesions. In some cases, blood tests may be ordered to rule out other causes of the rash, such as:
- White blood cell (WBC) count and differential
- Erythrocyte sedimentation rate (ESR)
- Total serum protein level
- Globulin levels
- Albumin level
- Potassium hydrochloride (KOH) test
Pityriasis rosea may be confused with an advanced stage of syphilis, so a rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test may be recommended to rule it out. An HIV test may also be considered.
What Is the Treatment for Pityriasis Rosea?
Pityriasis rosea goes away on its own in 6 to 8 weeks, and in some cases, no treatment is needed. Any treatment is aimed at relief of symptoms.
- Avoid hot water, sweating, harsh soaps, fragrances, wool, and synthetic fabrics, especially early in the disease as they may cause irritation
- For itching:
- Topical zinc oxide, calamine lotion, menthol-phenol, pramoxine, colloidal starch, or oatmeal baths can help relieve itching
- Oral antihistamines may also help stop the itch and they may help patients sleep since they cause drowsiness
- If the disease is severe or widespread, topical or oral steroids may be used
- Ultraviolet (UV) radiation therapy is effective but may leave dark spots at the site of the pityriasis rosea lesions
- Topical antifungal therapy may be used if superficial tinea infection is a concern
- The antiviral drug acyclovir may help shorten the duration of the condition
A dermatologist (a doctor who specializes in diagnosis and treatment of skin conditions) may need to be consulted if a patient has severe itching or requires prescription medications.
What Are the Complications of Pityriasis Rosea?
Pityriasis rosea is generally benign and most of the time will not come back after a patient has recovered, but in a small number of cases the condition recurs which may be a sign, there is another underlying condition causing the rash.
Pregnant women are in a high-risk group for serious complications from pityriasis rosea. In one small study, a majority of women who got pityriasis rosea in the first 15 weeks of pregnancy had miscarriages. Pregnant women should seek the advice of their obstetrician if they develop a rash.
How Do you Prevent Pityriasis Rosea?
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