Pityriasis rosea is a common skin disease. It appears as a rash that can last from several weeks to several months. The way the rash looks may differ from person to person. It most often develops in the spring and the fall, and seems to favor adolescents and young adults. Pityriasis rosea is uncommon in those over 60 years old. It may last months longer when it occurs in this age group. Usually there are no permanent marks as a result of this disease, although some darker-skinned persons may develop long-lasting flat brown spots.
The skin rash follows a very distinctive pattern. In 3/4 of the cases, a single, isolated oval scaly patch (the "herald patch") appears on the body, particularly on the trunk, upper arms, neck, or thighs. Often, the herald patch is mistaken for ringworm (tinea corporis) or eczema. Within a week or two more pink patches will occur on the body and on the arms and legs. These patches often form a pattern over the back resembling the outline of an evergreen tree with dropping branches. Patches may also appear on the neck and, rarely, on the face. These spots usually are smaller than the "herald" patch. The rash begins to heal after 2-4 weeks and is usually gone by 6-14.
Sometimes the disease can cause a more severe skin reaction. Some patients with this disease will have some itching that can be severe, especially when the patient becomes overheated. Occasionally there may be other symptoms, including tiredness and aching. The rash usually fades and disappears within six weeks but can sometimes last much longer. Physical activity, like jogging or running, or bathing in hot water may cause the rash to temporarily worsen or reappear. In some cases, the patches will reappear up to several weeks after the first episode. This can continue for many months.
The cause is unproven. It definitely is not caused by a fungus or bacterial infection. It also is not due to any known type of allergic reaction. This condition is not a sign of any type of internal disease. Since it is neither contagious nor sexually transmitted, there is no reason to avoid close or intimate contact when one has this eruption.
There is some evidence that it is a relapse of Human Herpes Virus type 7 (HH7) infection, as this virus has been isolated from blood, skin lesions, and white blood cells (lymphocytes) of pityriasis rosea patients. In other people HH7 is only found in the lymphocytes. This virus infects most of us as children, and we develop immunity to it. This is the reason it is so very uncommon for other members of the same household to come down with pityriasis rosea at the same time.
A dermatologist can usually diagnose the condition quickly with an examination, but at times the diagnosis is more difficult. The numbers and sizes of the spots can vary and occasionally the rash can be found in an unusual location, such as the lower body or on the face. When there is no "herald" patch, reactions to medications, infection with fungus or syphilis (a type of VD), or other skin diseases may resemble this rash. The dermatologist may order blood tests, skin scrapings or even may take a biopsy from one of the spots to examine under a microscope to reach a diagnosis.
Treatment may include external and internal medications for itching. Aveeno oatmeal baths, anti-itch medicated lotions and steroid creams may be prescribed to combat the rash. Lukewarm, rather than hot, baths may be suggested. Strenuous activity, which could aggravate the rash, should be discouraged. Ultraviolet light treatments given under the supervision of a dermatologist may be helpful. Recently, both the antiviral drug Famvir and the antibiotic erythromycin have been claimed to produce healing in one to two weeks. For severe cases a few days of oral anti-inflammatory medications such as prednisone may be necessary to promote healing. For mild cases, no treatment is required as this disease is not a dangerous skin condition.
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