Fall and Spring are the peak seasons to see pityriasis rosea (PR), a common but little known skin rash. Anyone can develop pityriasis rosea, although you're more likely to develop it between the ages of 10 and 30. It's pink, it's itchy and most definitely annoying. Yet the vast number of Americans have never heard of it.

No one is certain what causes pityriasis rosea. It is not a bacterial infection nor is the rash contagious. Since the onset of the rash is often associated with a recent low grade temperature or upper respiratory illness, most dermatologists suspect PR is the result of a viral infection. However, no infectious agent has been isolated. Like chicken pox, most patients only develop PR once in a lifetime. The actual rash of pityriasis rosea is not thought to be contagious in the classic sense, as few family members ever develop the rash. Some day I'll regret saying this, but for the 100's of PR patients I've seen over the years, I've never developed it.

Here A Spot, There A Spot, Everywhere A Spot, Spot

The vast majority of patients will develop a "herald patch" or "mother spot" long before the rest of the rash puts in an appearance. The herald patch is usually the largest spot of pityriasis rosea, measuring up to several centimeters in diameter, and precedes the development of the rash by days or a few weeks.

Small salmon pink oval patches (approximately one centimeter in size) with a "collarette" of scale rapidly form on the torso, abruptly stopping at the neck and hips. The spots of PR align themselves in an angular Christmas tree pattern on the chest and back.

The presence of this thin white scale periodically results in a misdiagnosis of "ringworm" (or fungus). Pityriasis rosea is typically a simple clinical diagnosis and does not require testing. But occasionally a confusing case can be solved through the use of a simple skin scraping called a KOH which will show the absence of a fungal infection. Rarely a skin biopsy may be performed.

It's not unusual to see stray patches develop on the extremities, neck and face. And since life is never complete without extremes, there is always the unfortunate patient covered head to toe.

Pityriasis rosea can have a somewhat different appearance in patients with darker complexions. The rash can seem bumpy, both in texture and look, and the smally bumps coalesce into oval patches. There may be less scale and the centers of the oval may have a duskier hue. Nevertheless, it is the same skin disorder and the treatment remains the same.

In adults, the appearance of PR can be mimicked by secondary syphilis, so I usually get a screening blood test. Syphilis is usually clinically obvious to spot, but I wouldn't want to miss a case.

To my knowledge, there are no reports of fetal anomalies when a pregnant woman has had PR or been exposed to PR as there are with the TORCH set of viral infections or Fifth's Disease.

Six Weeks Longing For Comfort And Joy

The rash typically arises over a 2 week period, remains stable for another 2 week period, and resolves over the next 2 weeks. In all, PR usually lasts approximately 6 weeks. There are occasional patients who have long term PR, but this is unusual. If a case of PR hasn't cleared within 8-10 weeks, I'll usually perform a workup to verify nothing has been overlooked.

Currently, there is no treatment available which clears the rash. It's one of those occasions when you just have to leave it alone and let it clear by itself. And ultimately the rash vanishes leaving the skin looking the way it did before. The exception to the rule may be those with darker complexions who may find some post inflammatory hyperpigmentation (brown skin discoloration) remains for several months until it has a chance to fade.

And while there may be no treatment for the rash itself, PR itches. Itching is by far the most common complaint, second only to the appearance of the rash itself. Therapy is aimed at controlling the discomfort. Itching is always worse at night. I suspect this is because during the day patients are distracted by work, family, school and a bevvy of other commitments. But once the head hits the pillow, there's no escaping the itch. There simply is nothing else to think about.

Comfort control may not be easy but there is certainly no lack of treatment options to try. OTC topical relief includes:

• Prax Lotion
• PrameGel
• Caladryl Clear Lotion
• LMX 4% Topical Anesthetic Cream - 30gm

Soaking in California Baby Super Sensitive No Fragrance Bubble Bath or adding approximately 1/3 of a box of baking soda to the bath water can also be soothing. Oral antihistamines, including prescription Atarax (hydroxyzine) or OTC Zyrtec, help alleviate itching and are particularly useful at bedtime.

Topical steroids can help reduce the inflammation associated with the eruption and thus reduce itching. The highest potency nonprescription option is 1% hydrocortisone contained in creams like .

One topical prescription antihistamine cream on the market, Zonolon, can rapidly reduce the itching. However, it isn't meant for full body use particularly on a long term basis. Should Zonolon (doxepin) be absorbed through the skin (this potential increases with more widespread use), it can actually cause drowsiness. Use it sparingly according to your doctor's directions.

Some dermatologists will treat patients once or twice with ultraviolet light (UVB) which can help reduce itching. Light therapy isn't for everyone, but presents an option in a retractable case of itching.

All in all, PR is an annoying, itchy rash that dermatologists see seasonally that ultimately goes away without a trace.

Thank you for reading this newsletter. I hope you have found it informative.

Audrey Kunin, M.D.

(Any topic discussed in this article is not intended as medical advice. If you have a medical concern, please check with your doctor.)

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