Pityriasis rosea

Latest update 29/06/2010

Definition

• An acute self-limiting condition, probably infective in origin

Key diagnostic features

• Age - tends to affect younger people, often between the ages of 10-35
• Clinical features
  • A herald patch precedes the main rash by a few days. It is larger than subsequent lesions, usually 2-5 cm in diameter, bright-red with fine scale and a sharply demarcated border
  • Distribution of the main rash – predominantly affects the trunk but can involve the limbs and occasionally the face in children. Lesions on the trunk tend to run along the lines of cleavage parallel to the ribs giving a Christmas tree-like appearance
  • Morphology - small oval dull-pink lesions with a fine peripheral collarette of scale
  • An important, although uncommon condition not to overlook is that of secondary syphilis. Lesions on the trunk can appear similar to those of pityriasis rosea, but additional sites such as the palms and soles are frequently affected

Management

• Provide a patient information leaflet
• The rash often resolves within 3-6 weeks
• An emollient or mild topical steroid may be needed if the rash is itchy

	Figure 1 - Pityriasis rosea with herald patch (arrow)
	Figure 2 - Pityriasis rosea Lesions on mid trunk running along long axis of ribs
	Figure 3 - Close up of figure 2
	Figure 4 - Pityriasis rosea The differential diagnosis could include a viral exanthem, a drug eruption or guttate psoriasis Herald patch present in left iliac fossa
	Figure 5 - Close up of figure 4
	Figure 6 - Secondary syphilis Faint red / brown patches most prominant in this patient on the mid-lower back
	Figure 7 - Secondary syphilis. Same patient as above