Pityriasis Rosea

Aka: Pityriasis Rosea

1. Epidemiology
   1. Ages 10 to 50 years (peaks age 20 to 30 years)
   2. No gender predisposition
   3. Seasonal variation: more common in spring and fall
2. Pathophysiology
   1. Papulosquamous eruption
   2. Thought to be of infectious etiology (Viral Exanthem)
3. Symptoms
   1. Pruritus (25% of cases)
   2. Other symptoms present in only 5% of patients
   3. Viral prodrome-type constitutional symptoms
      1. Headache
      2. Malaise
      3. Arthralgias
      4. Chills
   4. Nervousness
   5. Gastrointestinal symptoms
      1. Vomiting
      2. Diarrhea or Constipation
4. Signs
   1. Herald Patch (initial presenting lesion)
      1. Annular Lesion
         1. Erythematous border with fine scale
         2. Central clearing
      2. Single oval Macule on trunk
      3. Diameter: 2 to 10 cm
   2. Christmas tree Rash (Follow skin Cleavage Lines)
      1. Onset occurs 7-14 days after herald patch
      2. Symmetric bilaterally
      3. Smaller than herald patch (<1 cm)
      4. Individual lesions appear similar to herald patch
         1. Small fawn or salmon colored oval Macules
         2. Peripheral scaly collarettes
         3. Central clearing
5. Differential Diagnosis
   1. See Annular Lesion
   2. Secondary Syphilis
      1. Unlike pityriasis, Syphilis affects palms and soles
   3. Nummular eczema
   4. Tinea Corporis
   5. Guttate Psoriasis
   6. Lichen Planus
   7. Medication or toxin reaction
      1. Arsenic
      2. Barbiturates
      3. Bismuth
      4. BCG vaccine
      5. Captopril
      6. Clonidine
      7. Gold
      8. Hepatitis B Vaccine
      9. Interferon
6. Labs
   1. Syphilis Serology (RPR)
   2. Skin biopsy for direct fluorescent Antibody
      1. Indicated only if Syphilis strongly considered
      2. Pityriasis Rosea will show dyskeratotic degeneration
7. Management (No effective treatment)
   1. Severe Pruritus
      1. See Pruritus Management
      2. Topical Corticosteroid
      3. Oral Antihistamine
      4. Calamine lotion or zinc oxide
   2. Severe Cases
      1. Ultraviolet A Light
      2. Ultraviolet B Light
      3. Systemic Corticosteroids
      4. Erythromycin for 2 weeks may be effective
         1. Sharma (2000) J Am Acad Dermatol 42:241-4
8. Course
   1. Spontaneous resolution within 6 to 8 weeks in 80% cases
   2. Recurrence in less than 3%
9. References
   1. Allen (1995) Cutis 56:198-202
   2. Hsu (2001) Am Fam Physician 64(2):289-96
   3. Kempf (2000) Arch Virol 154(8):1509-20
   4. Stulberg (2004) Am Fam Physician 69:97-94