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 pityriasis rosea (PR) has been hypothesized based upon the following observations:
●PR is sometimes preceded by a prodrome.
●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 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 HHV-6 in the pathogenesis of PR [
3,5,6]. Possible associations with HHV-8 and 2009-2010 pandemic H1N1 influenza A virus have also been reported [
7-9].
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 women than men. 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, pink or salmon-colored
lesion on the chest, neck, or back (
picture 1C, 1F) [
10].
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 dark-skinned individuals 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) [
11].
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 [
12].
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
"Dermatologic procedures", section on 'Potassium hydroxide (KOH) prep'.)
There
are typically no laboratory abnormalities with PR. 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 mm or 4
mm punch biopsy typically provides an adequate specimen for analysis.
(See
"Skin biopsy techniques", section on 'Punch biopsy'.)
In
doubtful cases, signs, symptoms, and laboratory abnormalities relevant
to the conditions listed in the differential diagnosis list will assist
in proper identification.
●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 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", section on 'Nummular dermatitis'.)
●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. 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 also can 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 [
14]. Other medications and procedures suspected of producing PR-like reactions are
omeprazole [
15],
terbinafine [
16], bone marrow transplantation [
17], interferon alpha 2A [
18],
naproxen [
19],
captopril [
20],
isotretinoin [
21], and bacillus Calmette-Guerin therapy [
22].
TREATMENT
General approach — Education, reassurance, and interventions for pruritus are sufficient for the management of most patients with PR.
Patient/parent education — Patients
with PR and parents of children with PR typically want information
about clinical course, infectivity, and relapse. We reassure patients
and parents 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.)
Topical antipruritic lotions that contain
pramoxine or menthol and oral antihistamines may also be helpful for reducing symptoms of pruritus [
13].
Severe cases — Although
the vast majority of patients with PR require no treatment or only
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 trials of 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 led to trials of antiviral therapy in patients with this disorder. (See
'Etiology' above.)
●Efficacy – The results of a few small trials suggest that oral
acyclovir
therapy (400 to 800 mg five times per day for one week) may accelerate
resolution of the clinical manifestations of PR. Larger, high-quality
trials would be useful for confirming these findings.
•In
a randomized trial without a placebo-control arm in which the
evaluators were unaware of treatment assignment, 64 patients with PR
(ages 10 to 60 years) received either
acyclovir 400 mg five times per day for one week or no treatment [
23].
Treatment with acyclovir significantly accelerated improvement in
erythema; after two weeks, the percentage of patients with a reduction
in erythema was 79 percent in the acyclovir group versus 27 percent in
the group that was not treated. By the fourth week, a reduction in
erythema was seen in 93 versus 61 percent of patients, respectively.
Scale also resolved more quickly in the acyclovir group, but the
difference between the groups was no longer statistically significant at
the four-week time-point.
•In a randomized trial in which 38 patients with PR were treated with a seven-day course of high-dose oral
acyclovir (800 mg given five times per day for adults, 20
mg/kg
given four times per day for children) and 35 patients with PR were
given vitamin C tablets as placebo, rapid reductions in erythema were
significantly more frequent in the acyclovir group compared with the
placebo group [
24].
By day 7, 53 percent of the 30 acyclovir-treated patients who returned
for reevaluation compared with only 10 percent of the 30 vitamin C
recipients who returned showed decreased or absent erythema in all skin
lesions. After 14 days, this endpoint occurred in 87 and 33 percent of
patients in the acyclovir and vitamin C groups, respectively.
•In a nonrandomized single-blind trial of 87 adults with PR, high-dose
acyclovir (800 mg five times daily for one week) was beneficial [
25].
Patients treated with acyclovir had more rapid resolution of lesions
(mean time to clearance 19 versus 38 days) and fewer new lesions after
one week of therapy.
•An unblinded randomized trial performed with 42 children and adults with PR found that a one-week course of
acyclovir (800 mg five times per day for adults and 20
mg/kg per day given in five divided doses for children) was more effective than a one-week course of
erythromycin (500 mg four times daily in adults and 40
mg/kg per day in four divided doses for children) for reducing the severity and duration of PR [
26].
The rationale for efficacy for
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 [
27,28].
●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.
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 (UV) light from natural
sunlight or phototherapy devices may have benefit in PR, data on
efficacy are limited. No randomized trials have been performed, leaving
uncertainty about the impact of this therapy. (See
"UVB therapy (broadband and narrowband)".)
●Efficacy –
Three split-body studies in which one-half of the body was treated with
broadband UVB suggest beneficial effects of phototherapy [
29-31].
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 UVA as a control [
31].
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 [
29].
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 [
30].
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. Narrowband UVB has not been specifically studied for PR,
but is presumed to have at least similar efficacy. Worsening of PR
following narrowband UVB phototherapy has been reported in one patient [
32];
however, it is unclear whether the exacerbation of disease was
secondary to phototherapy or the natural course of the disease [
33]. (See
"UVB therapy (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) [
34]. (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.
Other therapy
Macrolide antibiotics — The efficacy of oral
erythromycin
for PR is uncertain based upon conflicting efficacy data for
erythromycin and the failure of randomized trials of other macrolides to
find benefit in PR. Given the uncertain benefit of erythromycin and the
common gastrointestinal side effects associated with the drug, we do
not use erythromycin for the treatment of PR.
Controlled trials evaluating
erythromycin therapy include:
●A blinded, controlled trial that alternately assigned 90 patients to treatment or placebo found that
erythromycin (250 mg four times daily for 14 days) was effective in reducing both the duration and the severity of the disease [
35].
In this report, a complete response at six weeks of follow-up was noted
in 73 percent of patients in the treatment group compared with none in
the placebo group.
●A systematic review identified a small (n = 40) unpublished randomized trial of
erythromycin (250 mg every six hours for fourteen days), which the authors of the systematic review felt to be a good quality trial [
36].
Among the 34 evaluable patients, a higher percentage of those treated
with erythromycin achieved complete cure of rash at two weeks (77 versus
6 percent). Patients treated with erythromycin also had greater
improvements in itching.
●In
contrast to the above results, a trial of 184 patients with PR
published after the above systematic review found no benefit with two
weeks of oral
erythromycin (200 mg four times daily in adults; 20 to 40
mg/kg daily in four divided doses in children) started within seven days of the appearance of secondary lesions of PR [
37].
The trial was not randomized, evaluators were not blinded, and the
placebo 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. Despite the methodologic issues with this
trial, it is difficult to reconcile these results with the beneficial
outcomes discussed above. The authors argue that earlier trials did not
adequately identify a group of patients with a clear diagnosis of early
PR.
Also in contrast to the trials that support efficacy of
erythromycin, trials of
azithromycin and
clarithromycin
for PR have yielded unfavorable results. For example, a blinded
randomized trial in 49 children with PR found no statistically
significant benefit to five days of treatment with azithromycin (12
mg/kg per day, up to 500 mg per day) [
38].
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 superiority of a five-day course of azithromycin (12
mg/kg per day) over a multivitamin placebo [
39].
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 [
40].
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 — An
analysis of a case series of 61 women who developed PR during pregnancy
suggests that PR increases the risk for spontaneous abortion [
41].
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. Further studies are
necessary to clarify the impact of PR on pregnancy.
INFORMATION FOR PATIENTS — UpToDate
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level, and they answer the four or five key questions a patient might
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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
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SUMMARY AND RECOMMENDATIONS
●Pityriasis rosea is an acute, self-limited, exanthematous skin disease felt most likely to be due to a viral etiology. (See
'Introduction' above and
'Etiology' above.)
●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.)
●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.)
●The
diagnosis of pityriasis rosea 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.)
●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.)
●For
patients with severe presentations resulting in a significant negative
impact on quality of life, limited data suggest that oral
acyclovir
may be useful for shortening the course of pityriasis rosea.
Phototherapy is an additional treatment option. We suggest not treating
such patients with oral
erythromycin (
Grade 2C). Additional studies will be useful for confirming the efficacy of PR therapies. (See
'Severe cases' above and
'Other therapy' above.)
