Updated: 12/16/2021

Pityriasis Rosea

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  • Snapshot
    • A 20-year-old student presents to the school’s health clinic complaining of a scaly rash on his trunk. He recalls having a mild fever and headaches a few weeks prior, but did not think much of it. The lesions do not itch. He loves to play tennis and spends a lot of time outdoors and wear proper attire during activities. On exam, the lesions are primarily on his central trunk. His sun-exposed arms have no lesions on them.
  • Introduction
    • Common, self-limited papulosquamous eruption
      • three stages of disease
        • herald patch
        • secondary eruption
        • spontaneous resolution
  • Epidemiology
    • Children
    • Young adults
    • Rare above 35 years of age
  • ETIOLOGY
    • Pathogenesis
      • idiopathic
      • often associated with URI
      • seasonal pattern suggests viral etiology, though not confirmed
        • potential link to herpesvirus types 6 and 7
  • Presentation
    • Symptoms
      • prodrome or URI within a month of onset
      • little or no pruritus
    • Physical exam
      • herald patch, a single lesion
        • usually on the trunk
        • plaque with thin collarette of scale inside the border
      • eruption in 1-2 weeks
        • multiple smaller papules appear in “Christmas tree” distribution
          • oriented along Langer (skin cleavage) lines
        • rose-colored or violet
        • common clustering in lower abdominal and pubic area
      • resolution in 4-12 weeks
        • resolves spontaneously without scarring
        • may have post-inflammatory hypo- or hyper-pigmentation
  • Evaluation
    • Diagnosis from clinical exam and history
    • Diagnosis confirmed with skin biopsy
      • potassium hydroxide preparation to exclude Tinea spp. infections (Tinea versicolor and Tinea corporis)
    • If sexually active and palms and soles involved
      • serologic testing for secondary syphilis
  • Differential
    • Tinea corporis
    • Secondary syphilis (esp if palm and soles involved)
    • Tinea versicolor
    • Drug eruption
    • Guttate psoriasis
  • Treatment
    • Observation
      • lesions heal within 4-12 weeks
    • To hasten recovery
      • UVB from natural sunlight or in the dermatology office
      • oral erythromycin
    • If itchy
      • antihistamines
      • topical steroids
  • Complications
    • Post-inflammatory pigmentary changes
    • Relapse
  • Prognosis
    • Very good
    • Typically self-limited and self-resolving in 4-12 weeks
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Questions (2)

(M2.DM.17.4732) A 17-year-old male presents to the clinic with complaints of a new-onset rash. He describes initially seeing a circular lesion on his abdomen three days prior and then many smaller new lesions occurring in the following days. The skin lesions are generally asymptomatic, although some are intermittently itchy. His past medical history is significant for sickle cell trait and seasonal allergies. His medications include folic acid and fexofenadine as needed. In addition, he had a recent episode of sore throat associated with congestion and rhinorrhea for which he took azithromycin. He does well in school and is on the wrestling team. His temperature is 99.1°F (37.3°C), pulse is 60/min, blood pressure is 110/64 mmHg, respirations are 13/min, oxygen saturation is 99% on room air. Physical exam is notable for a diffuse rash on the trunk (Figure A). Which of the following is the most likely trigger of this patient’s skin condition?

QID: 108603
FIGURES:
1

Bacterial infection

0%

(0/26)

2

Fungal infection

38%

(10/26)

3

Viral infection

35%

(9/26)

4

Drug eruption

15%

(4/26)

5

Idiopathic

12%

(3/26)

M 6 E

Select Answer to see Preferred Response

(M2.DM.16.4694) A 7-year-old boy is brought to the pediatrician by his mother for complaints of a diffuse, itchy rash over his abdomen, back, and upper legs. The rash first appeared about 1 week ago. He has otherwise been well, and he has no known sick contacts. On exam he is afebrile and cooperative. His skin exam (Figure A) is notable for a single large, well-circumscribed pink plaque over his mid-abdomen, and many pink papules of varying sizes over his abdomen, back, and thighs. On follow-up a month later, the rash has largely resolved without intervention. What is the most likely diagnosis?

QID: 107822
FIGURES:
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Guttate psoriasis

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(0/13)

2

Pityriasis rosea

69%

(9/13)

3

Tinea versicolor

15%

(2/13)

4

Tinea corporis

15%

(2/13)

5

Urticaria

0%

(0/13)

M 6 E

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