Pityriasis rosea is a common papulosquamous disorder that tends to affect children and young adults once in their life. A second attack is rare. The cause is unknown although unproven theories include exposure to a viral agent. It is not contagious. Generally, a single herald or mother plaque develops several days prior to the full-blown rash. The herald lesion is redder, rounder, larger (2 — 5 cm), and more scaly than the plaques of the overall rash. The rash tends to appear on the trunk, but can also extend to the neck and extremities. Itching occurs in approximately 50% of cases. Typical plaque appearance is an oval shape that is salmon pink in color with delicate scaling on the periphery. Projecting from the spine, their axis runs down and out along the lines of the ribs in a 'fir tree' distribution. Strenuous physical activity (eg, running) or showering in hot water make the rash temporarily more visible. Although it can last longer, the rash usually lasts between 2 and 10 weeks and either spontaneously disappears or leaves several plaques to slowly fade. In either case, the rash will eventually disappear completely. Systemic symptoms are rare, but a few patients will complain of aching and fatigue.

There is no cure for pityriasis rosea other than time, but treatment may be prescribed for symptomatic relief. Treatment options include a topical steroid or other anti-itch cream to address pruritis. Sunlight or ultraviolet phototherapy may also help the itching. Scaling can be reduced with 1% salicyclic acid in soft white paraffin or emulsifying ointment.