Version May 2024
INTRODUCTION — Pityriasis rosea (PR) is an acute, self-limited, exanthematous skin disease characterized by the appearance of slightly inflammatory, oval, papulosquamous lesions on the trunk and proximal areas of the extremities (picture 1A-E). The diagnosis and management of this disorder are reviewed here.
ETIOLOGY — A viral etiology for PR has been hypothesized based upon the following observations:
●PR is sometimes preceded by a prodrome of headache, malaise, and pharyngitis.
●It occasionally occurs in small case clusters.
●It has not been shown to be associated with bacterial or fungal organisms.
This supposition is reinforced by the finding of viral-like particles in PR biopsy specimens examined with the electron microscope [1]. A significant literature supports the hypothesis that PR is a manifestation of human herpesvirus 7 (HHV-7) reactivation [2,3]. However, others have failed to detect HHV-7 deoxyribonucleic acid (DNA) sequences and antigens in a significant number of PR cases, arguing against a causative role for this agent [4].
Some studies have also implicated human herpesvirus 6 (HHV-6) in the pathogenesis of PR [3,5,6]. Possible associations with human herpesvirus 8 (HHV-8), the 2009 to 2010 pandemic H1N1 influenza A virus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have also been reported [7-11]. (See "COVID-19: Cutaneous manifestations and issues related to dermatologic care", section on 'Considerations for vaccination to prevent SARS-CoV-2 infection'.)
More study is needed before this issue can be definitively resolved.
CLINICAL FEATURES — PR is largely a disease of older children and young adults. It is slightly more common in females than males. A prodrome of headache, malaise, and pharyngitis may occur in a small number of cases, but except for itching, the condition is usually asymptomatic.
In 50 to 90 percent of cases, the eruption begins with a "herald" or "mother" patch, a single round or oval, sharply delimited lesion on the chest, neck, or back (picture 1C, 1F) [12]. The herald patch is usually 2 to 5 cm in diameter. The lesion soon becomes scaly and begins to clear centrally, leaving the free edge of the cigarette paper-like scale directed inwards toward the center. This clinical finding is often described as a "collarette" of scale.
A few days or one to two weeks later, oval lesions similar in appearance to the herald patch, but smaller, appear in crops on the trunk and proximal areas of the extremities (picture 1A-E, 1G). The long axes of these oval lesions tend to be oriented along the lines of cleavage of the skin. This characteristic arrangement is most evident on the back, where it is emphasized by the oblique direction of the cleavage lines in that location. This morphologic pattern has been referred to as a "fir tree" or "Christmas tree" distribution.
The eruption spreads centrifugally or from the top down over the course of a few days. Erythema gradually subsides, desquamation is completed, and the eruption fades, leaving few residual changes, except postinflammatory dyspigmentation. In most cases the papules and plaques resolve in four to six weeks; occasionally the disease will persist for several months. Postinflammatory hyperpigmentation is a common sequela in individuals with darkly pigmented skin and often takes several months or longer to resolve.
In children, the distribution of the lesions is often atypical, involving the scalp and face; it may be completely "inverse," affecting the face and distal extremities, while sparing the trunk, or may be concentrated in the pubic, inguinal, and axillary regions (picture 1G-J) [13]. The lesions themselves also are sometimes atypical in children; they may be folliculo-papular, vesicular, pustular, urticarial, or purpuric. PR generally has only mild effects on quality of life in children [14].
Oropharyngeal abnormalities have been reported in patients with PR. In a review of 527 patients with PR, 149 patients (28 percent) had oropharyngeal lesions, with petechial, macular, and papular eruptions as the most common findings [15]. Oropharyngeal swabs for culture were performed in 90 patients and showed normal flora in all patients. Mucosal biopsies were not performed.
DIAGNOSIS — The presence of a herald patch by history or on examination, the characteristic morphology and distribution of the lesions, and the absence of symptoms other than pruritus combine to make PR an easy diagnosis in most instances. However, the herald patch can resemble tinea corporis so closely that potassium hydroxide (KOH) examination of scales for dermatophyte hyphae may be necessary to distinguish these conditions. (See 'Differential diagnosis' below and "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation'.)
There are typically no laboratory abnormalities with PR. Serologic testing to rule out syphilis is recommended for sexually active patients. The cutaneous manifestations of secondary syphilis resemble PR (picture 3B). (See 'Differential diagnosis' below and "Syphilis: Screening and diagnostic testing", section on 'Approach to testing'.)
Skin biopsy is rarely necessary, but when performed shows focal parakeratosis with or without acanthosis, spongiosis, a perivascular infiltrate of lymphocytes and histiocytes, and occasionally extravasation of red cells (picture 2). The biopsy picture is characteristic but not pathognomonic. A 3 or 4 mm punch biopsy typically provides an adequate specimen for analysis. (See "Skin biopsy techniques", section on 'Punch biopsy'.)
DIFFERENTIAL DIAGNOSIS — A differential diagnosis should always be considered in patients who present with lesions that are suspicious for PR [16]. When the diagnosis is in question, a skin biopsy can be performed. A potassium hydroxide preparation is useful for ruling out fungal infections (see "Skin biopsy techniques", section on 'Punch biopsy' and "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation'):
●Secondary syphilis – The papulosquamous eruption of secondary syphilis can closely resemble PR; however, unlike the latter, secondary syphilis often presents with red-brown macules on the palms and soles (picture 3A-B). Patients with secondary syphilis also may recall the appearance of a chancre and will lack a history of a herald patch. In patients in whom secondary syphilis is suspected, appropriate serologic testing should be performed. (See "Syphilis: Screening and diagnostic testing" and "Syphilis: Epidemiology, pathophysiology, and clinical manifestations in patients without HIV", section on 'Clinical manifestations'.)
●Guttate psoriasis – Guttate psoriasis is a variant of psoriasis that most frequently affects children and young adults. Small, erythematous, scaly plaques are distributed primarily on the trunk (picture 4). The scale tends to be coarser than the scale associated with PR, and a herald patch does not precede the eruption. Guttate psoriasis frequently is associated with a preceding streptococcal infection. (See "Guttate psoriasis".)
●Tinea corporis – The herald patch of PR may be mistaken for tinea corporis, which may also present with an annular plaque with peripheral scale (picture 5). A KOH preparation from a lesion of tinea corporis will reveal fungal hyphae. (See "Dermatophyte (tinea) infections", section on 'Tinea corporis'.)
●Tinea versicolor – Tinea versicolor presents with hypopigmented or hyperpigmented macules that are most commonly located on the neck and trunk (picture 6A-B). Unlike in PR, erythema is absent or minimal. The scale in tinea versicolor is fine, and lesions lack the peripheral rim of scale that is often seen in PR. A KOH preparation easily confirms a diagnosis of tinea versicolor. (See "Tinea versicolor (pityriasis versicolor)".)
●Nummular eczema – Nummular eczema presents with intensely pruritic, coin-shaped plaques that may range in size from 2 to 10 cm (picture 7A-B). Involvement of the extremities is more common in nummular eczema than in PR. Serous exudate may be visible in acute lesions of nummular eczema. (See "Overview of dermatitis (eczematous dermatoses)", section on 'Nummular eczema'.)
●Pityriasis lichenoides chronica – Pityriasis lichenoides chronica (PLC) is an uncommon condition that is characterized by recurrent crops of erythematous to brown scaly papules on the trunk and proximal extremities (picture 8A-B). Lesions may be asymptomatic or pruritic, and spontaneously regress over the course of weeks to months. PLC most commonly occurs in children and young adults. The disorder may persist for years. (See "Pityriasis lichenoides chronica".)
Other disorders that should be considered in the differential diagnosis of PR include Lyme disease, human immunodeficiency virus (HIV) seroconversion illness, and drug eruptions. Testing for HIV should be performed in patients with risk factors for or symptoms suggestive of HIV infection. (See "Acute and early HIV infection: Pathogenesis and epidemiology" and "Screening and diagnostic testing for HIV infection".)
Therapeutic gold injections can also cause eruptions that mimic PR closely. These eruptions do not represent allergic reactions but are dose related and can be managed safely by reduction in dose size and the frequency of administration [17]. Other medications and procedures suspected of producing PR-like reactions are omeprazole [18], terbinafine [19], bone marrow transplantation [20], interferon alfa-2a [21], naproxen [22], captopril [23], isotretinoin [24], bacillus Calmette-Guerin therapy [25], and coronavirus disease 2019 (COVID-19) vaccination [26-28].
TREATMENT
General approach — Education, reassurance, and interventions for pruritus are sufficient for the management of most patients with PR [29].
Patient and caregiver education — Patients with PR and caregivers of children with PR typically want information about clinical course, infectivity, and relapse. We reassure patients and caregivers that PR typically spontaneously resolves within two to three months, is thought to have a low likelihood for transmission, and does not recur in most patients. (See 'Prognosis' below.)
Pruritus — Clinical experience has shown that topical corticosteroids in the medium potency range (group 4 or group 5) are helpful in the control of itching (table 1). They can be applied to the pruritic areas two or three times daily for two to three weeks. Long-term use of topical corticosteroids without medical supervision should be avoided because of risk for corticosteroid-induced skin atrophy. (See "Topical corticosteroids: Use and adverse effects", section on 'Adverse effects'.)
Topical antipruritic lotions that contain pramoxine or menthol and oral antihistamines may also be helpful for reducing symptoms of pruritus [16,29].
Severe cases — Although the vast majority of patients with PR require no treatment or only topical treatment to control pruritus, there is some evidence that oral acyclovir and ultraviolet light may accelerate clinical improvement. Routine treatment with these interventions is not recommended because efficacy data are limited, and PR typically resolves without treatment. We reserve acyclovir or ultraviolet light therapy for patients with severe symptoms associated with a significant negative effect on quality of life.
Acyclovir — The proposed link between PR and human herpesvirus (HHV) led to trials of antiviral therapy in patients with this disorder (see 'Etiology' above):
●Efficacy – Few randomized trials have evaluated the efficacy of acyclovir, and high-quality studies are lacking. A systematic review and meta-analysis of randomized trials that assessed outcomes of PR therapy within two weeks (a criterion intended to minimize the impact of spontaneous resolution) found moderate-quality evidence in support of acyclovir therapy [30]. The meta-analysis included three trials (with a total of 141 patients) that compared acyclovir (400 or 800 mg given five times per day for one week) with placebo, vitamin C (as a control), or no treatment. Acyclovir therapy was associated with a greater likelihood for good or excellent improvement in skin erythema within two weeks (risk ratio [RR] 2.45, 95% CI 1.33-4.53). No serious adverse effects occurred in the included trials.
The impact of acyclovir therapy on PR-associated itch is uncertain. One randomized trial (n = 27) found patients who received acyclovir were less likely to achieve resolution of itch at two weeks than patients who received placebo (RR 0.34, 95% CI 0.12-0.94) [31]. However, an unblinded trial (n = 24) that randomly assigned patients with PR to either acyclovir plus calamine lotion and cetirizine or calamine lotion and cetirizine alone found resolution of itch more likely in the acyclovir group (RR 4.50, 95% CI 1.22-16.62) [30,32].
The rationale for benefit of acyclovir therapy remains unclear. In vitro studies demonstrating that acyclovir has poor antiviral activity against HHV-6 and HHV-7 raise questions about the etiology of PR and the reasons for the efficacy of acyclovir [33,34].
●Administration – Doses for adults with PR range from 400 to 800 mg of acyclovir given five times per day for one week. Improvement is expected within one to two weeks. Further study may clarify whether the effects of a low-dose regimen for acyclovir (400 mg three times daily for seven days) are similar [32].
Acyclovir therapy is generally well tolerated. Acute renal failure is a potential severe adverse effect. Adverse effects of acyclovir are reviewed separately. (See "Acyclovir: An overview", section on 'Toxicity'.)
Phototherapy — Phototherapy has an extensive history of use for a variety of papulosquamous and inflammatory disorders of the skin as well as for pruritus. Although clinical experience suggests that ultraviolet light from natural sunlight or phototherapy devices may have benefit in PR, data on efficacy are limited (see "UVB phototherapy (broadband and narrowband)"):
●Efficacy – Three split-body studies in which one-half of the body was treated with broadband ultraviolet B (UVB) suggest beneficial effects of phototherapy [35-37]. As an example, a study of 101 children and adults with PR found statistically significant reductions in PR severity scores on the side of the body treated with broadband UVB four times per week, but not on the side treated with a very low dose of ultraviolet A (UVA) as a control [37]. Patients received a mean of five treatments. In addition, in a study in which broadband UVB was used to treat one-half of the body for 10 treatments over two weeks in 17 patients with extensive PR, and a very low dose of UVA was given contralaterally as a control, UVB significantly decreased disease severity during the treatment period. However, the difference in effect was no longer present two weeks after the completion of treatment [35]. UVB had no effect on pruritus in this study. In contrast, a split-body study of 20 patients with PR found that broadband UVB therapy decreased the extent of disease and pruritus [36].
Narrowband UVB devices, which emit UVB in the range of 311 to 313 nm rather than the 290 nm to 320 nm range emitted by broadband UVB devices, are now commonly used for the treatment of skin diseases previously treated with broadband UVB. A randomized trial in which 100 patients with PR were randomly assigned to narrowband UVB phototherapy (three times weekly for four weeks) or no treatment found greater improvement in disease severity scores and itching among patients treated with narrowband UVB [38]. Worsening of PR following narrowband UVB phototherapy has been reported in one patient [39]; however, it is unclear whether the exacerbation of disease was secondary to phototherapy or the natural course of the disease [40]. (See "UVB phototherapy (broadband and narrowband)".)
UVA1 phototherapy also may have some benefit for the treatment of PR, although it has much more limited availability. In an uncontrolled study of patients with extensive PR, UVA1 was associated with improvements in disease severity, and 12 out of 15 patients noted improvement in pruritus (mean number of treatments = 6.5±1.8) [41]. (See "UVA1 phototherapy".)
In clinical practice, exposure to outdoor sunlight is sometimes suggested to patients with PR. However, data on the efficacy of this mode of exposure to ultraviolet light are lacking.
●Administration – The best regimen for phototherapy is unclear. When treating PR with phototherapy, we most frequently treat with broadband or narrowband UVB two to three times per week. Improvement is expected within the first two to three weeks of treatment. Additional studies are necessary to confirm the efficacy of phototherapy for PR and to determine the optimal regimen for phototherapy.
Short-term side effects of phototherapy include erythema, pruritus, dry skin, and blistering. Side effects of phototherapy are reviewed in detail separately. (See "UVB phototherapy (broadband and narrowband)", section on 'Short- and long-term adverse effects' and "UVA1 phototherapy", section on 'Adverse effects'.)
Other therapy
Macrolide antibiotics — The efficacy of oral erythromycin for PR is uncertain, and other macrolides, including azithromycin and clarithromycin, do not appear to be effective for PR. Given the conflicting efficacy data, we do not utilize macrolide antibiotics for the treatment of PR:
●Erythromycin – While some studies have found oral erythromycin effective for accelerating resolution of PR, data are limited, and additional studies would be useful for confirming benefit. Moreover, some studies suggest erythromycin might be less effective than acyclovir. Examples of relevant studies include:
•A 2019 systematic review of randomized trials that assessed treatment outcomes for PR within two weeks (a criterion intended to minimize the impact of spontaneous resolution) identified two placebo-controlled, randomized trials [30]. Although each trial found patients treated with erythromycin (1 g per day given for one or two weeks) more likely to achieve complete cure than patients in the placebo groups, a meta-analysis of these trials (total of 86 patients) did not find a difference in effect (RR 4.02, 95% CI 0.28-56.61). High heterogeneity between the two trials was a limitation of the meta-analysis. One of the trials, an unpublished trial (n = 40), found erythromycin (1 g per day for two weeks) effective for reducing the patient-reported itch score (RR 3.95, 95% CI 3.37-4.53) [30].
•A trial in which 30 patients with PR were randomly assigned to acyclovir (800 mg five times per day) or erythromycin (400 mg four times per day) for 10 days found patients given acyclovir were more likely to achieve a complete response after eight weeks (87 versus 40 percent) [42]. In addition, an unblinded, randomized trial performed with 42 children and adults with PR found a one-week course of acyclovir (20 mg/kg five times per day for children and 800 mg five times per day for adults) more effective than a one-week course of erythromycin (40 mg/kg per day in four divided doses for children and 500 mg four times per day for adults) for reducing the severity and duration of PR [43].
•A trial that alternately assigned 90 patients to erythromycin treatment or placebo and assessed response after six weeks found that patients who received erythromycin (250 mg four times daily for 14 days) were more likely to achieve a complete response within two weeks [44]. A complete response was noted in 73 percent of patients in the treatment group compared with none in the placebo group.
•A controlled study of 184 patients with PR found no benefit with two weeks of oral erythromycin (200 mg four times daily in adults and 20 to 40 mg/kg daily in four divided doses in children) started within seven days of the appearance of secondary lesions of PR [45]. The trial was not randomized, evaluators were not blinded, and the control was an emollient cream rather than a pill. No patient in either arm of the trial achieved complete clearance of lesions at two weeks, and there were also no differences in complete clearance between the arms at weeks 4, 6, or 8.
●Other macrolides – Trials of azithromycin and clarithromycin for PR support inefficacy of these therapies. A randomized trial in 49 children with PR found no benefit of five days of treatment with azithromycin (12 mg/kg per day, up to 500 mg per day) [46]. At four weeks, there were similar percentages of complete (60 versus 42 percent) and partial (28 versus 29 percent) responses with azithromycin and placebo. A randomized trial in 70 children and adults with PR also failed to find a five-day course of azithromycin (12 mg/kg per day) more effective than a multivitamin placebo [47]. Similarly, clarithromycin was ineffective in a randomized trial in which 60 children and adults with PR were given one-week courses of clarithromycin (200 or 250 mg twice daily) or placebo pills [48].
Systemic glucocorticoids — Although systemic glucocorticoids may improve manifestations and pruritus of PR, routine treatment with systemic glucocorticoids is not recommended due to limited efficacy data and concern for increased risk for relapse after treatment. In a 12-week trial in which 70 patients with PR were randomly assigned to either oral prednisolone (20 mg per day for five days, 15 mg/day for five days, then 10 mg/day for five days) or placebo, prednisolone therapy was associated with faster improvement in pruritus and the disease severity score [49]. However, benefit of prednisolone was no longer evident by week 4 for pruritus or by week 8 for the disease severity score, and at week 12, six relapses of PR after complete or near complete clearance had occurred in the prednisolone group compared with one relapse in the placebo group. The proportion of patients who relapsed in each group is unclear because the number of patients who achieved complete clearance was not reported.
PROGNOSIS — Patients should be advised that the rash may persist for two to three months; no follow-up is necessary as long as it resolves within this time. New lesions may occur during this period but should disappear spontaneously. Relapse after resolution is uncommon [3].
PREGNANCY — Data on the impact of PR on pregnancy are limited and conflicting. An analysis of a case series of 61 women who developed PR during pregnancy suggested that PR increases the risk for spontaneous abortion [50]. Spontaneous abortions occurred in 8 of 61 women (13 percent) who developed PR during pregnancy and 8 of 14 women (57 percent) who developed PR within the first 15 weeks of gestation.
However, the frequency of spontaneous abortion has been lower in other series and comparable with rates in patients without PR. In one case series, spontaneous abortions occurred in only 2 of 46 pregnant individuals with PR (4 percent) [51]. No spontaneous abortions occurred in a subsequent retrospective study of 33 pregnant individuals with PR, and elevated rates of other birth complications were not observed [52].
Some data suggest that certain factors may influence risk for various negative pregnancy outcomes [50,51,53]. An analysis of pooled data from 99 patients in case reports and case series suggested a greater likelihood for unfavorable pregnancy outcomes (preterm delivery, low birth weight, or spontaneous abortion) among pregnant individuals with extensive or prolonged PR, onset of PR earlier in pregnancy, or associated extracutaneous symptoms [51]. The timing of onset of PR did not seem to be a relevant factor for pregnancy complications in one subsequently published case series (n = 33) [52].
Further studies are necessary to clarify the impact of PR on pregnancy.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Pityriasis rosea (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Etiology – Pityriasis rosea (PR) is an acute, self-limited, exanthematous skin disease felt most likely to be due to a viral etiology. (See 'Introduction' above and 'Etiology' above.)
●Clinical features:
•Cutaneous findings – The eruption commonly begins with a "herald" or "mother" patch, a single round or oval, rather sharply delimited pink or salmon-colored lesion on the chest, neck, or back, 2 to 5 cm in diameter. A few days or a week or two later, oval lesions similar in appearance to the herald patch, but smaller, appear in crops on the trunk and proximal areas of the extremities (picture 1A-E). The long axes of these oval lesions tend to be oriented along the lines of cleavage of the skin. (See 'Clinical features' above.)
•Associated symptoms – A prodrome of headache, malaise, and pharyngitis may occur in a small number of cases, but except for itching, the condition is usually asymptomatic. (See 'Clinical features' above.)
●Diagnosis – The diagnosis of PR is typically made based on the history of a herald patch and the clinical appearance of the rash. Laboratory testing is sometimes needed to exclude other conditions such as secondary syphilis. (See 'Differential diagnosis' above.)
●Treatment:
•General approach – Most patients do not require therapy. For patients with mild itching who desire therapy, we suggest treatment with medium-potency topical corticosteroids (table 1) (Grade 2C). (See 'Pruritus' above.)
•Patients with severe presentations – For patients with severe presentations of PR who desire treatment to accelerate improvement of the skin manifestations, we suggest treatment with oral acyclovir rather than oral erythromycin (Grade 2C). Phototherapy is an alternative treatment option. Additional studies will be useful for confirming the efficacy of PR therapies. (See 'Severe cases' above and 'Other therapy' above.)
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