Pityriasis Rosea

This disorder is a common, but unexplainable, reaction. The initial lesion, "herald patch", is red and scaly, followed in 1 to 2 weeks by widespread, oval, scaling, fawn-colored macules 4 to 5 mm in diameter over the trunk and proximal extremities. Pityriasis rosea is usually an acute self-limiting illness that lasts 4 to 8 weeks. It is not highly infectious.