Pityriasis Rosea

Pityriasis Rosea

Pityriasis rosea (PR) is a common, harmless human skin disease which presents as numerous patches of pink or red oval rash, mainly on the torso. The condition appears to be entirely non-contagious, or of extremely limited virulence. PR can affect members of either sex, at any age. Symptoms are not thought to recur at all, though the fact that a viral agent is likely involved means that radically different symptoms might be produced by the same agent later in life, and the link could go entirely unnoticed.

Symptoms

The symptoms of this condition include: * Large patches of pink or red, flaky, oval-shaped rash on the torso. Due to similarities early in the disease course, the primary differential diagnoses are ringworm, psoriasis and discoid eczema. * A single, large red "herald" patch may occur 1 to 20 days before smaller, more numerous patches of rash. Occasionally, the "herald" patch may occur in a 'hidden' position (in the armpit, for example) and not be noticed immediately. The "herald" patch may also appear as a cluster of smaller oval spots, and be mistaken for acne. Rarely, it does not present at all. * The "herald" patch may be preceded by a sore throat of varying severity. * The more numerous oval patches generally spread widely across the chest first, following the rib-line. Small, circular patches may appear on the back and neck several days later. It is unusual for lesions to form on the face, but they may appear on the cheeks or at the hairline. * As the rash begins to subside on the torso, it may spread to the groin and the extremities. These lesions are usually more short-lived. However, males may have several lesions on their penis, which can be aggravated by the stretching of the skin involved in normal erection, and these may last substantially longer. Sexual intercourse should be avoided in such cases, and care should be taken to avoid secondary bacterial infection if the skin actually cracks. * About one-in-four people with PR suffer from mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. Luckily, this tends to fade as the rash develops and does not usually last through the entire course of the disease. * The rash may be be accompanied by low-grade headache, fever, nausea and fatigue. Over-the-counter medications can help manage these. * While PR can resemble the initial rash of secondary syphilis, the latter can be easily excluded by testing. Syphilis is thus no longer considered a valid differential diagnosis. (Furthermore, PR never involves the palms of the hands or soles of the feet, as secondary syphilis almost always does, nor does it form the whitish syphilis lesions known as condylomata lata.) * Like most skin conditions that produce a widespread rash, PR can be damaging to a patient's self-image. It also causes fear about scarring in most patients. Doctors should take care to calm such worries.

Treatment

No treatment is usually required. In most patients, the condition lasts only a matter of weeks; in some cases it can last longer (up to six months). A doctor should be consulted, if only to rule out other conditions. While no scarring has been found to be associated with the rash, itching and scratching should be avoided. Irritants such as soap should be avoided, too; a soap containing moisturizers (such as goat's milk) may be used, however, and generic moisturizer can help to manage over-dryness. In cases of severe symptomatic itching, topical or oral steroids may be prescribed. (Steroids provide relief from itching and improve the appearance of the rash, but they also ensure that the new skin that forms after the rash subsides will take a longer time to match the surrounding skin color). Doctor-operated UV therapy, or simple exposure to sunlight, also helps in some cases; serious precautions should be taken to avoid sunburn, though, as this will only exacerbate the problem.

Epidemiology

Because research resources tend to be allocated to more serious conditions (an entirely self-limiting, non-contagious skin disease is not high on the list of medical priorities) there is limited information about the true range and prevalence of the disease. The overall prevalence of PR in the United States has been estimated to be 0.13% in men and 0.14% in women. It most commonly occurs in those between the ages of 10 and 35. Though multiple family members have been known to contract the disease at roughly the same time, this may be co-incidental; the fact that PR is far more common in the spring and autumn months points to environmental factors and not person-to-person contact as the main disease vector. Reported levels from different dermatologic centers worldwide vary widely (from 0.03% to 3%). An increase in the prevalence of PR has been reported in a study out of Uganda, while no change in the prevalence of PR has been reported in a similar study conducted in Sweden. PR is not limited geographically, and has no racial predilections. It has been reported in the United Kingdom, United States, Canada, Nigeria, Sudan, Brazil, Lagos, Singapore, Turkey, Kuwait, and Hong Kong.