Pityriasis rosea is a skin disease of uncertain origin characterized by lesions bordered by collar-like areas that tend to peel off in tiny scales. Pityriasis comes from the Greek word for bran, pityron, because the flakes of skin shed from the lesions resemble small pieces of wheat bran. Rosea comes from a Latin word that means “rose-colored” or “pink.”
Pityriasis rosea is a common benign skin disease, or exanthem, that was first described by a French physician named Camille Gibert in 1860.
It is classified as a papulosquamous disorder, which means that its lesions are marked by small raised areas (papules) as well as scaly areas. Pityriasis rosea begins in 60%–90% of patients with a pinkish-brown or salmon-colored herald patch sometimes called a mother patch—on the chest, back, or neck.
The herald patch is a small spot when it first appears, but enlarges over a period of several days to form a circular or oval-shaped area between 3/4-in and 2-1/2 in in diameter. The herald patch develops a scaly border known as a collarette, and is often misdiagnosed in its early stages as eczema or ringworm.
The herald patch is followed within 5–10 days by a series of similar but smaller oval-shaped patches that appear on the patient’s chest, back, and legs, although the general eruption may appear as rapidly as a few hours after the herald patch or as long as three months later.
The general rash lasts for about six weeks. The smaller patches range between 1/8 in and 1/2 in in diameter, and are sometimes described as resembling cigarette paper.
Lesions on the trunk and abdomen are commonly distributed along the midline of the body in a pattern resembling the outline of a Christmas tree. The lesions of the general eruption are found most commonly on the chest, back, and upper arms, but are sometimes limited to such smaller areas of the body as the armpits, groin, palms of the hands, or feet.
Between 9% and 16% of patients develop ulcers or plaques inside the mouth. It is relatively unusual, however, for patches to appear on the face. A small minority of patients may have the herald patch as the only sign of pityriasis rosea.
Pityriasis rosea is a common skin disorder, accounting for 3% of visits to dermatologists in the United States and Canada. The overall prevalence of the disease in the general North American population is thought to be about 0.13% in males and 0.14% in females. It is rare in infants and the elderly; most cases are diagnosed in persons between the ages of 10 and 35.
Pityriasis rosea tends to cluster in families, which is one reason why some researchers have been investigating various viruses as possible causes; however, it is not known to spread by casual contact. The disease affects all races and ethnic groups equally.
Pityriasis rosea may occur at any time of year but is most common in temperate climates in the spring and fall.
Causes and symptoms
The cause of pityriasis rosea is debated as of early 2004. Various researchers have reported isolating a mycoplasma (a type of gram-negative bacterium), a picornavirus, and human herpesviruses 6 and 7 from skin samples of patients diagnosed with the disease, but these findings are not yet considered definitive.
Certain medications, including diphtheria vaccines, barbiturates, gold, bismuth compounds, captopril (Capoten), metronidazole (Flagyl), isotretinoin (Accutane), clonidine (Catapres), omeprazole (Prilosec), penicillamine (Cuprimine or Depen), and terbinafine (Lamisil) have been reported to cause skin rashes that resemble the lesions of pityriasis rosea. High levels of emotional stress appear to increase the severity of the skin lesions in some patients.
The most common symptom associated with the lesions of pityriasis rosea is pruritus or itching, which affects about 75% of patients, with 25% reporting severe itching.
Many patients find that athletic activity or hot weather makes the itching worse. In addition to pruritus, some patients have prodromal symptoms, which are warning symptoms that occur before the herald patch appears.
Prodromal symptoms of pityriasis rosea may include fever, loss of appetite, nausea, headache, joint pains, and swelling of the lymph nodes. Lymph node swelling is more common among African Americans diagnosed with the disease than among Caucasian or Asian Americans.
The diagnosis of pityriasis rosea is usually made through taking a patient history—with particular attention to prescription medications—and a skin biopsy ordered by a dermatologist.
Although there is no blood test for pityriasis rosea itself, most primary care physicians will order a rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) blood test to screen for syphilis.
The reason for this precaution is that the lesions of pityriasis rosea resemble the skin rash associated with secondary syphilis. The skin biopsy is done to distinguish between pityriasis rosea and such other skin diseases as lichen planus, psoriasis, ringworm, Kaposi’s sarcoma, and seborrheic dermatitis.
Pityriasis rosea is a self-limiting disease, which means that it goes away on its own even without alternative or allopathic treatment. Both mainstream physicians and naturopaths, however, recommend adding a cup of oatmeal or baking soda to a tub of warm (not hot) water to minimize itching.
In addition, patients whose lesions increase in size or number due to emotional stress may be helped by hydrotherapy, aromatherapy, meditation, or other therapies intended to reduce stress. Massage therapy, however, is contraindicated because the disease usually affects large areas of skin.
Homeopathic practitioners suggest the following remedies for pityriasis rosea, to be taken in 6C potency four times daily for 7 days:
- Arsenicum. Recommended for patients whose rash is accompanied by anxiety, restlessness, and thirst.
- Radium bromide. For patients whose lesions are fiery red in color, burning, and painful.
- Natrum muriaticum. For patients whose lesions have a red appearance under thin white scales, or whose pruritus is made worse by warmth or exercise.
In addition, a homeopathic remedy known as Urtica urens is available in cream or ointment form for direct application to affected areas.
Allopathic treatment of pityriasis rosea is directed toward symptom relief, as the cause of the disease is still uncertain. To relieve the itching, the doctor may prescribe calamine lotion, zinc oxide ointment, oral antihistamine medications, or topical ointments containing corticosteroids or a combination of phenol and 25% menthol.
Some physicians prescribe creams containing pramoxine, a local anesthetic. Steroid medications taken by mouth are not recommended unless the pruritus is extremely severe; although these drugs relieve itching, they may also prolong the course of the disease or make the lesions worse.
Some patients are benefited by exposure to sunlight or by treatment with ultraviolet light; however, there is some risk that the skin lesions will develop hyperpigmentation (become darker than the surrounding skin) after ultraviolet treatment. Hyperpigmentation is most likely to occur in African American patients.
There is no need to keep children with pityriasis rosea from attending school, as the disease is not considered contagious.
The prognosis for patients with pityriasis rosea is excellent. The disease does not cause long-term health problems, is not dangerous even during pregnancy, and usually clears completely in 6–8 weeks. A few patients have lesions that last as long as 3–4 months, but fewer than 3% of patients experience recurrences.
As the cause of pityriasis rosea is still debated as of 2004, there are no known preventive measures.