Pityriasis Rosea

Pityriasis rosea ( PR ) is an acute , benign , self limiting papulosquamous exanthem of an unknown etiology

First described by Gilbert in 1860 Pityriasis means rose colured scale Also known as pityriasis circinata , roseola annulata and herpes tonsurans maculosus Happens worldwide with no genetic or racial predisposition Most common in people aged 10-35 yrs Seen rarely in children < 10 Slight female preponderance Community based incidence is reported to be 172.2 per 100 ,000 persons year Prevalence for young people aged between 10-29 yrs is reported to be 0.6 % other studies quote that the approximate incidence of PR is 0.5 % to 2 % Seen in all seasons but some studies suggest an increase in spring and fall.

Cause -The cause is not clear and is widely debated Various agents . causes have been postulated for e.g- infective agents as viruses , bacteria , spirochetes- non infective etiologies as atopy and autoimmunity- Infectious cause is widely implicated and it is said that the following points support an infectious cause- outbreak in clusters ie infectious agent is circulating in the community- recurrence of infection outside the acute phase is rare ie long lasting immunity - many patients...