Pityriasis rosea

Background

Normal dermal anatomy.

• Mild inflammatory exanthem
  • May be caused by HHV 6 and 7
  • 70% preceded by URI
• Most common 10-35yr old
• Not contagious
• Spontaneous resolution occurs within 4-12wk

Evaluation

Pityriasis rosea on back

Pityriasis rosea on front

Herald patch

• Begins with single, "herald,"patch (salmon-colored, fine scaling)
  • 1-2 weeks prior to generalized eruption
  • Larger lesion (Herald Patch) that resembles the later smaller lesions
    • Typically on the abdomen
• Secondary maculopapular rash with plaques following Langer Lines ("Christmas tree" pattern)
  • Typically follows rip distribution
• Pruritus can be moderate to severe
• Consider RPR or VDRL to rule out syphilis

Differential Diagnosis

• Psoriasis
• Tinea corporis
  • Usually not as widespread
• Pityriasis versicolor
  • Also has fine scaling but KOH is diagnostic

Plaques

• Psoriasis
• Bowen disease
• Discoid lupus erythematosus
• Drug eruption
• Erythema annulare centrifugum
• Lichen planus
• Lichen simplex chronicus
• Nummular dermatitis (nummular eczema)
• Parapsoriasis
• Pityriasis rosea
• Seborrheic dermatitis

Management

• Lasts 8 to 12 weeks
• Reassurance about the self-limited nature
• Natural sunlight may speed up resolution
• Pruritus
  • Antihistamine, topical steroids
    • Triamcinolone 0.1% - Adults
    • Hydrocortisone 1% - Children
  • Other
    • Zinc oxide
    • Calamine lotion
  • Systemic steroids are generally not recommended.
• Rash or pruritus beyond 12 weeks: reconsider original diagnosis
  • Consider biopsy to confirm the diagnosis

Disposition

• Discharge