Integumentary system ORGAN SYSTEMS

Pityriasis rosea

Christmas tree rash, or pityriasis rosea, is an acute, self-limiting, papulosquamous eruption with a duration of 6-8 weeks.

  • Non-contageous


Associated with:

  • Human herpesvirus 6 (HHV6) or human herpesvirus 7 (HHV7)

Clinical features

URTI precedes all other symptoms (69% cases)

  • Single, 2-10-cm oval red “herald” patch
    • Appears on abdomen (classically) or in ‘hidden’ positions (in the armpit, for example)
    • May also appear as a cluster of smaller oval spots, and be mistaken for acne (D/D)
  • 7–14 days after the herald patch,
    • Many small (5–10 mm) patches of pink/red, flaky, oval-shaped rash appear on the torso.
    • Christmas-treedistribution
      • Spread widely across the chest first, following the rib-line
  • Small, circular patches may appear on the back and neck several days later.


Clinical diagnosis

A patient is diagnosed as having pityriasis rosea if:

  1. On at least 1 occasion/clinical encounter, he/she has all essential + atleast 1 optional clinical features
  2. On all occasions/clinical encounters related to rash, he/she does not have any of the exclusional clinical features.

The essential clinical features are the following:

  1. Discrete circular or oval lesions,
  2. Scaling on most lesions, and
  3. Peripheral collarette scaling with central clearance on at least lesions.

The optional clinical features are the following:

  1. Truncal and proximal limb distribution, (< 10% of lesions distal to mid-upper-arm and mid-thigh),
  2. Orientation of most lesions along skin cleavage lines, and
  3. A herald patch (not necessarily the largest) appearing at least 2 days before eruption of other lesions, from history of the patient or from clinical observation.

The exclusional clinical features are the following:

  1. Multiple small vesicles at the centre of two or more lesions,
  2. ≥ 2 lesions on palmar/plantar skin surfaces, and
  3. Clinical/serological evidence of secondary syphilis.


Condition usually resolves on its own, and treatment is not required.

Supportive therapy:

  • Sunlight/UVB-phototherapy
    • Help the lesions disappear faster if started during the first week of eruption
  • Itching:
    • Lotions, oral antihistamines, and/or topical glucocorticoids

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