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the initial rapidly enlarging oval-shaped red papulosquamous lesion, usually on the trunk, heralding the widespread eruption of pityriasis rosea, and preceding the latter by 7-14 days.
herald patchDermatology A lesion early pityriasis rosea consisting of a solitary oval, 1-10 cm annular macule with raised border and fine, adherent scales. See Pityriasis rosea.
A solitary oval patch of scaly skin that appears several days before the generalized rash of pityriasis rosea.
See also: patch