Case 3: Sudden Rash
Tuesday, January 11th, 2011This 22-year-old female presented with a sudden dissemination of a rash across her trunk. She had had a round scaly area on the right breast for several days but then suddenly noticed oval, slightly itchy, spots over her front and back that morning. She feels well.
1. What is the diagnosis?
Click to see the answerThis is pityriasis rosea. A benign condition, thought to have a viral basis. Affecting young adults between late teens and middle age. It is self limiting, resolving in four to six weeks.
2. What is the significance of the larger spot on the right breast?
Click to see the answerThe more generalised rash is normally preceded by a single lesion one to two weeks earlier, known as the ‘ herald patch’. On close examination this has a characteristic structure. There is a central red area ringed by a ring of fine scales, surrounded by a further red area. The herald patch generally occurs on the trunk. The more generalised rash is usually, although not always, itchy. It is symmetrical, normally limited to the trunk, and characteristically has a ‘ Christmas tree’ pattern. It is made up of oval patches, of 1-2 cm in length.
3. What are the implications for contacts?
Click to see the answerAlthough this condition tends to occur in clusters in the spring and autumn, it is not directly contagious.
4. What is the prognosis?
Click to see the answerThe condition is entirely self-limiting. Transient pigmentation changes may remain.