What is pityriasis rosea?

Causes and Symptoms

Pityriasis rosea is primarily a skin

disease of children and young adults, with females being more commonly affected than males. The initial lesion is a characteristic eruption seen on the trunk called the herald or mother patch, as it signals the onset of lesions to come. This is a scaly pink plaque which is around one to two centimeters in diameter, slightly raised above the surface, with central salmon-colored wrinkles. This lesion should be differentiated from that of syphilis and ringworm.

The herald patch is followed in about two weeks by a crop of similar but smaller lesions all over the trunk. The pink scaly oval papules are distributed along the skin tension lines in the trunk and result in a so-called Christmas tree distribution. The lesions may be mild to moderately pruritic (itchy) and will resolve spontaneously in four to six weeks, without any specific treatment. Other symptoms may involve mild aches and fatigue.

The exact cause of this exanthem (eruptive disease) is not known, but it is believed to result from exposure to various viruses. Most patients appear to have a positive recent history of influenza or an upper respiratory tract infection. The eruption typically appears in spring and fall and appears to cluster among close contacts; however, it is not believed to be highly contagious.

Treatment and Therapy

There is no specific treatment for pityriasis rosea, and usually none is required, as the disease is self-limited and resolves without treatment in four to six weeks. Pruritus is usually mild and can be treated with antihistamines and calamine lotion. If itching is severe, then topical steroids and a short, tapered dose of systemic
steroids may be administered. Ultraviolet B (UVB) radiation is another treatment option. Patients are also advised to avoid hot showers and strenuous activity, as sweat and water appear to exacerbate the rash.

Perspective and Prospects

The term pityriasis is derived from the Greek pityron, meaning “scales.” The term, initially applied to include all those skin disorders that were characterized by fine scales, is presently used only with modifiers such as rosea, alba, or versicolor. Rosea means “pink,” and therefore pityriasis rosea describes pink-colored, fine, scaly lesions.

It is important clinically to distinguish the herald patch from other skin conditions. Therefore, a blood test for syphilis should be included for differential diagnosis. Also, ringworm, which requires treatment with antifungal agents, should be ruled out.

About 3 percent of the patients with pityriasis rosea experience recurrences, and no systemic manifestations have been demonstrated.

Bibliography

Chuh, Antonio A. T. “Pityriasis Rosea: Roles of the Dermatology Nurse.” Dermatology Nursing 16, no. 2 (April 1, 2004): 130–136.

Parker, James N., and Philip M. Parker. Pityriasis Rosea: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. San Diego, Calif.: ICON Health Publications, 2004.

Kasper, Dennis L., et al., eds. Harrison’s Principles of Internal Medicine. 18th ed. New York: McGraw-Hill, 2012.

Montemayor-Quellenberg, Marjorie. "Pityriasis Rosea." Health Library, September 26, 2012.

Rakel, Robert E., ed. Textbook of Family Practice. 8th ed. Philadelphia: W. B. Saunders, 2011.

Tapley, Donald F., et al., eds. The Columbia University College of Physicians and Surgeons Complete Home Medical Guide. Rev. 3d ed. New York: Crown, 1995.

Vorvick, Linda J. "Pityriasis Rosea." MedlinePlus, October 14, 2012.