pityriasis rosea, a self-limited skin disease in which a slightly scaling pink macular rash spreads over the trunk and other unexposed areas of the body. A characteristic feature is the herald patch, a larger, more scaly lesion that precedes the diffuse rash by several days. The smaller lesions tend to line up with the long axis parallel to normal lines of cleavage of the skin. Mild itching is the only symptom. The disease lasts 4 to 8 weeks and rarely recurs. Compare pityriasis alba.
