Updated: 11/19/2016

Pityriasis Rosea

Review Topic
  • A 10-year-old boy is brought to his dermatologist for a developing rash. A couple of weeks ago, he recovered from a common cold. A week after, he developed an oval rash on his chest. Thinking it was a fungus infection, his parents applied anti-fungal cream to the area. However, a week after the first lesion appeared, he developed multiple smaller rashes in his lower abdomen. They are sometimes itchy, but only mildly so.
  • Common, self-limited papulosquamous eruption
  • Pathogenesis
    • idiopathic
    • often associated with URI
    • seasonal pattern suggests viral etiology, though not confirmed
      • potential link to herpesvirus types 6 and 7
  • Epidemiology
    • children
    • young adults
  • 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
    • resolution in 4-12 weeks
      • resolves spontaneously without scarring
  • Diagnosis from clinical exam and history
  • Diagnosis confirmed with skin biopsy
    • potassium hydroxide preparation to exclude Tinea spp.
Differential Diagnosis
  • Tinea corporis
  • Secondary syphilis (especially if palm and soles involved)
  • Tinea versicolor
  • Drug eruption
  • Guttate psoriasis
  • Observation
    • lesions heal within 4-12 weeks
  • Natural sunlight
Prognosis, Prevention, and Complications
  • Prognosis
    • very good
    • typically self-limited and self-resolving in 4-12 weeks
  • Complications
    • relapse

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