Pityriasis rosea

Pityriasis rosea is a common, acute, self limiting, papulosquamous condition thought to be due to HHV7 (1).

Many drugs have been linked with an extensive and often prolonged form of the disease e.g. - captopril, barbiturates, clonidine, gold (2).

Presentation is with fawn-coloured, large (around 2-10 cm in diameter), slightly raised, oval scaly patches which typically develop on the limbs and trunk - commonly known as an initial 'herald' lesion. Often there is a collarette of scale present at the margin in some lesions

Most commonly seen in children and young adults (2).

A systematic review concluded that "..When compared with placebo or no treatment, oral acyclovir probably leads to increased good or excellent, medical practitioner-rated rash improvement. However, evidence for the effect of acyclovir on itch was inconclusive. We found low- to moderate-quality evidence that erythromycin probably reduces itch more than placebo.." (3)

Click here for example images of pitryriasis rosea

Reference:

• (1) Turchin I, Adams SP, Enta T. Dermacase. Canadian Family Physician2004;50:41-50
• (2) Stulberg DL, Wolfrey J. Pityriasis Rosea. AFP 2004;69(1)
• (3) Contreras-Ruiz J et al. Interventions for pityriasis rosea Cochrane Database Syst. Rev. 2019 Oct 30;2019(10):CD005068.