Pityriasis Rosea

Pityriasis rosacea
  • P. rosea is a common scaly disorder, occuring usually in children and young adults (10-35 years).
  • Characterized by round/oval pink brown patches with a superficial, centrifugal scale, distributed over trunk in a Christmas tree pattern.
  • The disease is thought to be viral disease, is self limiting, and subsides in 6-12 weeks.
  • The exact etiology is not known, but it is considered to be a viral disease; Human Herpes virus 6 (HHV 6) and Human Herpes virus 7 (HHV 7) may play a role.
Clinical manifestations of P. rosea
  • The disease starts with an upper respiratory prodrome or a mild flu.
  • After 1-2 weeks, Annular erythmatous plaque appears on trunk that is referred to as mother patch or herald patch. 
  • Over the next 1-2 weeks, fresh patch appear all over the trunk, in a Christmas tree configuration or Fir tree Configration.
  • The lesions are pinkish in white skin, hence the name rosea.
  • However, on the dark Indian skin the lesions are skin coloured or brown.
  • The most characteristic clue for the diagnosis is the presence of a fine scale at the edge of the lesion referrred to as centrifugal scale or collarette scales or cigarette paper scales.
  • Lesions subside with hyperpigmentation.
  • Trunk is involved predominantly, Sometimes (in 20% of patients) lesions occur predominantly on extremities and neck (inverse pattern).
Exam Question
  • Pityriasis rosea is a self limiting disease.
  • Hanging curtain sign seen in Pityriasis Rosea.
  • Lesions of pityriasis rosea are distributed mostly on the trunk.
  • A 25 year old male presents with multiple erythematous annular plaques with peripheral collarette of scales arranged predominantly over trunk.Pityriasis Rosea is the most probable diagnosis.
  • Herald patch ,moderate itching ,low grade fever may be seen in Pityriasis Rosea.
  • 'Fir-tree' type of distribution is seen in Pityriasis Rosea.
  • HHV-7 viral association is found in pityriasis rosea .
  • Etiology of Pityriasis rosea is Herpes Virus.
  • Christmas tree appearance in skin is seen in Pityriasis Rosea.
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