Pityriasis rosea is a mild, but common, skin condition. Characterized by scaly, pink, inflamed skin, the condition can last from four to eight weeks and usually leaves no lasting marks. Pityriasis rosea is a self-limiting, salmon-colored patch that is followed by a spreading rash. The lesions are 1-2 cm in diameter, and are firmly attached at their borders and loose in the center, which gives them a cigarette-paper appearance. They last from 4-12 weeks, occurring more often in spring and fall.
The main symptoms of pityriasis rosea are the appearance of the herald patch followed by a more diffuse rash of smaller patches. The patches tend to be oval, scaly, and dry to the touch. They may be pink, red or brown and generally appear on the abdomen, back, neck, arms and legs. Only rarely do the patches appear on the face. Typically, the disease begins with the appearance of a single large, pink, scaly, oval patch, called the "herald patch." This patch is approximately 1 inch to 2 inches long. It tends to have a salmon-colored center surrounded by a darker pink ring, which some patients mistake as a sign of ringworm. Within about two weeks, many smaller patches appear, sometimes hundreds of them. They are mildly itchy and appear mainly on the abdomen and back. On the back, the patches tend to line up along the ribs, giving the rash a distinct "Christmas tree" pattern. The rash goes away on its own, usually within two months. Any skin discoloration from the rash will fade after another few 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.
There are no treatments that cure pityriasis rosea; the disease must run its course. However, the itching can be treated in several ways. For mild itching, an over-the-counter anti-itch ointment (such as calamine lotion) or corticosteroid cream (such as Cortizone-10 or Cortaid) may be enough to provide relief. For more severe itching, stronger steroid creams may be prescribed. For itching that occurs mainly at night, oral antihistamines may reduce itching and make you drowsy enough to fall asleep more easily. In very severe cases in which the rash lasts longer than usual, or if the rash covers a large part of the body, ultraviolet (UV) light therapy may be recommended. Doses of UV-B rays, similar to the sun's rays, are given by exposing the skin to the light rays for short periods of time over several days. The skin may turn slightly red, similar to a mild sunburn. The red spots may appear more prominently after a hot shower or bath and after heavy physical activity. The condition doesn't get worse, the rash simply becomes more noticeable.