玫瑰糠疹雖然不算罕見，大小教科書也都一直會提到，但在臨床實戰上卻沒有那麼容易診斷，甚至需要動用到診斷要件。這種疾病儘管不會有嚴重併發症，卻會造成病人的恐慌，也一直是皮膚科醫師的重要課題。
Chapter 31 :: Pityriasis Rosea
:: Matthew Clark & Johann E. Gudjonsson
鄭煜彬(20200117)
What is the meaning of pityriasis rosea?
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Pink (rosea) scales (pityriasis).
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EPIDEMIOLOGY
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When is PR found commonly?
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In colder months, but not supported by
all studies.
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Why is PR thought as infectious disease?
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PR usually has clustering of cases.
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Which gender has higher prevalence?
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Female(F:M=1.39: 1, especially pregnant women)
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What age group has highest prevalence?
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10-35 years(teenagers & young adults)
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Does PR relapse?
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Yes, but rare(only 1.8% to 3.7%).
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CLINICAL FEATURES
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HISTORY
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What is the first lesion of classic PR?
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The herald patch: a solitary lesion on
the trunk or less commonly an extremity.
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How long is the time between herald patch
& secondary(2°) eruptions?
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On average
l 2 weeks in adults
l 4 days in children
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Where is the locations of the 2°
eruptions of PR?
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Trunk & proximal extremities
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What is the prodromal symptoms before or
with the 2° eruption?
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Malaise, nausea, headache,
gastrointestinal, & upper respiratory symptoms (flu-like), & lymphadenopathy.
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What is the most common symptom of PR
rashes?
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Pruritus(severe: mild/moderate: absent=
1:2:1)
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What is the variants in pediatric
patients(< 10 y/o)?
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Relapsing form: single (multiple is rare)
episode of relapse within 1 year of the initial episode.
Persistent form: last for > 12 weeks without
Interruption
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What is the features of relapsing PR?
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Lack a herald patch, shorter lived, fewer,
& more localized lesions.
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What is the features of persistent PR?
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Has a herald patch, more common oral
manifestations
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How long is the duration of pediatric PR?
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on average 16 days (shorter than that on
adults)
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CUTANEOUS FINDINGS
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What is the features of classic herald patch?
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One/multiple well-demarcated, thin, oval
to round, pink/rose/colored/erythematous/ hyperpigmented plaque with a
slightly depressed center & fine collarette of scale in the periphery.
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Where is the locations of herald patch?
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Trunk (50%)>extremities>neck>>
dorsal feet/face/ scalp/genitalia
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How big is the size of herald patch?
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>3 cm(2-10 cm
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How much is the incidence of the herald
patch?
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80% (12% to 94%)
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How much is the incidence of the multiple
herald patch?
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5%
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How long is the time between the herald
patch & 2° eruptions?
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2 weeks (a few hours to 3 months), but
sometimes no 2° eruptions.
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What is the features of 2°
eruption of PR?
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Multiple, round-to-oval, 0.5- to 1.5-cm, light
pink macules, papules, & plaques (smaller herald patch)
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Where is the locations of 2°
eruption?
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Trunk & proximal extremities>>
distal extremities >>palms & soles.
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What is the specific distribution of 2°
eruptions of PR?
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“Christmas tree” distribution on the
upper chest & back: long axis of the lesions parallel to lines of
cleavage (ribs)
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How about the course of 2°
eruption?
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Appears 2 weeks after herald patch, occurs in crops every few days,
reaches its maximum 2 weeks later,
then disappears in 45 days.
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How about the relationship between PR &
sun-exposure?
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Some are confined to sun-protected skin; others
are confined to sun-exposed skin. Most are randomly distributed.
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What is the atypical forms of 2°
eruption?
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Eczematous, papular, follicular,
vesicular, urticarial, pustular, & purpuric forms.
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What is the configuration of vesicular
lesions of PR?
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They are arranged in a rosette.
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What age group has higher incidence of
vesicular lesions?
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Children & young adults
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How much is the incidence of mucosal
lesions in PR cases?
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16% (uncommon)
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What is the clinical features of oral
lesions of PR?
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They can be punctate hemorrhagic,
ulcerative, erythematous macules, plaques, bullous, & annular lesions. Ulcer is most common.
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What is the atypical variants of PR?
(hint: 5, distribution)
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Unilateral(not cross midline), localized(1
truncal site), & inverse(children’s folds, face, distal limbs),
blaschkoid, acral variants.
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COMPLICATIONS
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What is the complication of PR in the
healthy individuals?
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Anxiety & depression, no long-term
complications
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What is the complication of PR in the
pregnants?
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PR before 15 weeks: higher miscarriage
PR after 15 weeks: higher premature delivery
± hypotonia, weak motility, & hyporeactivity
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ETIOLOGY & PATHOGENESIS
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What pathogens may induce pityriasis
rosea?
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HHV-7 and/or HHV-6
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What is the relationship between PR &
HHVs?
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PR is the T cell infiltrate (cell-mediated
immunity) caused by primary infection or reactivation of HHV-7 and/or HHV-6.
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What is the changes of cells, cytokines,
& proteins in PR?
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⇧ (1)
CD4-to-CD8 ratio & Langerhans cells
(3) IL-17, IFN-γ (4)VEGF, interferon-inducible protein-10 (CXCL10).
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DIAGNOSIS
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What is the clinical diagnostic criteria
of PR?
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3 essential + at least 1 optional, no
exclusion
Essential features (圓環屑)
l Discrete circular or oval
lesions
l Scaling on most lesions
l Peripheral collarette of
scale with central clearance on ≥ 2
lesions.
Optional features (軀近、肋、先)
l A truncal & proximal
limb distribution, < 10% lesions distal to the middle of arms & thighs
l Distribution of most lesions
along the ribs
l A herald patch ≥ 2 days before the eruption.
3 exclusion features
l Central, multiple small vesicles
at ≥ 2 lesions
l Most lesions on palmar or
plantar skin
l Clinical or serological evidence of 2° syphilis.
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LABORATORY TESTING
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When should you check lab in PR patients?
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To rule out 2° syphilis
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PATHOLOGY
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What does PR look like in pathology?
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Subacute eczema + extravasated RBC
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What are the features of PR?
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Epidermis: focal/multifocal/confluent
parakeratosis, orthokeratosis, mild acanthosis; a thinned granular layer; &
spongiosis+ lymphocyte exocytosis
Dermis: a superficial perivascular
lymphocytic infiltrate + extravasated RBC
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What is the difference of pathology
between herald patch & 2° eruption?
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No difference. But herald patch has thicker
acanthosis & deeper infiltration.
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DIFFERENTIAL DIAGNOSIS
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What diseases can be the differential diagnosis
of PR?
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Papulosquamous disorders:
l Nummular eczema (round, no X’mas tree)
l Guttate psoriasis(no X’mas tree, no herald patch)
l Lichen planus (pruritic, chronic, violet, more distal limbs, no
collarette of scales)
l Pityriasis lichenoides (chronic, relapsing course, no herald patch,
lesions in various stages, limbs)
l Tinea corporis(KOH)
l Parapsoriasis(no X’mas tree, no herald patch, chronic course)
l Seborrheic dermatitis(face & scalp),
l Secondary syphilis (oral/palmoplantar lesions, persistent LAP,
serology+, split papules, moth-eaten alopecia, condyloma lata ).
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What are the possible culprits of
drug-induced PR?
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Barbiturates,
captopril, clonidine, gold, metronidazole, d-penicillamine, isotretinoin,
levamisole, NSAID, omeprazole, terbinafine, imatinib, & adalimumab.
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Why does adalimumab induce PR-like
eruption?
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Adalimumab dampens T-helper 1 cell
response and predispose to viral infection or reactivation.
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What is the difference between PR &
drug-induced PR?
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Drug-induced PR has more hyperpigmentation
& lichenoid morphology.
More interface dermatitis, dyskeratotic
keratinocytes, & eosinophils in pathology.
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CLINICAL COURSE AND PROGNOSIS
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How long is the duration of PR?
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Average: 45 days (range: 2 weeks to 5
months)
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What is the definition of persistent PR?
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Eruptions last > 3 months (12 weeks)
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What is the cutaneous sequela of PR?
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Post-inflammatory hyper/hypopigmentation
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MANAGEMENT
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What should you do to most cases of PR?
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No treatment is necessary because it is self-limited
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How to treat PR?
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l Topical: steroids & antihistamines (just improve pruritus)
l Oral: acyclovir (800 mg 5 time) >> macrolide (erythromycin
& azithromycin)
l UVB
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How to prevent PR?
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No way.
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