Published on 18/03/2015 by admin
Filed under Dermatology
Last modified 18/03/2015
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Anna E. Muncaster
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Pityriasis rosea is a common, self-limiting, papulosquamous disorder affecting the trunk and limbs, usually seen in the 10–35-year age group. It has a classical clinical appearance, is associated with little or no constitutional upset, but can have associated itching. Secondary syphilis and drug eruptions are diagnostic pitfalls.
Pityriasis rosea usually resolves spontaneously after approximately 6 weeks and, if asymptomatic, reassurance is all that is required. An infectious etiology, most likely viral, is strongly favored, and although several studies have suggested an association with human herpes viruses 6 and 7, an equal number have failed to show a causal link. Studies have also looked at but failed to prove an etiological role for human herpes virus 8 and there have been two case reports of a pirtyriasis rosea-like eruption occurring in patients with H1N1 influenza A virus. There have been case reports of pityriasis rosea-like eruptions after many drugs including captopril, ketotifen, and more recently adalimumab and etanercept. However, there is no evidence that true pityriasis rosea is drug induced.
For patients who do require treatment, topical corticosteroids may be helpful, although evidence for this is purely anecdotal. Emollients and oral antihistamines have also been mentioned as being of some benefit as has ultraviolet light.
Studies have shown that UVB can reduce itch and disease severity, and a study using low dose UVA1 phototherapy showed significant reduction in the severity and extent of the disease but little impact on pruritus.
For patients with more extensive severe eruptions oral prednisolone can be tried; however, this should be used with caution, as there are also reports that oral steroids can exacerbate the condition.
A trial of oral erythromycin produced complete clearance after 2 weeks in the majority of patients. The best results with all the treatments above have been obtained when treatment is started within the first 2 weeks of the appearance of the eruption. Later studies of erythromycin in pityriasis rosea have shown conflicting results. There has been one case report of vesicular pityriasis rosea responding to 10 days of oral erythromycin at a dose of 250 mg four times a day, but two further trials, one using oral erythromycin and one using azithromycin, have failed to show any benefit.
Oral acyclovir has been used in pityriasis rosea at both high and low dose. One study compared high dose acyclovir with erythromycin and found acyclovir to be more effective. There has also been one case report of pityriasis rosea clearing following oral acyclovir and one showing clearance with dapsone.
Consider mycological examination
Consider syphilis serology
Parsons JM. J Am Acad Dermatol 1986; 15: 159–67.
Treatment of Skin Disease Comprehensive Therapeutic Strategies 4e
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Topical corticosteroids
Emollients
Oral antihistamines
