Herald Patch
The initial solitary, oval, salmon-coloured plaque with a collarette of fine scaling that precedes the generalised eruption in pityriasis rosea.
Full Definition
The herald patch is a pathognomonic feature of pityriasis rosea, typically measuring 2–5 cm in diameter and appearing on the trunk one to two weeks before the secondary eruption. Its trailing collarette of scale (inner edge of scale) is an important distinguishing feature from tinea corporis, which has a leading-edge scale. Editors must hyphenate 'herald patch' only if used attributively before a noun (e.g., 'herald-patch distribution'). The term is always two words and is not capitalised unless beginning a sentence.
Usage
Usage note: Two words, no capitalisation. Hyphenate only in attributive use before a noun. Do not confuse with 'primary lesion', which is a broader term.
In Context
- "A 4 cm herald patch was identified on the left lateral trunk, with a fine collarette of scale at its inner border." — Dermatology clinical description
- "The patient recalled noticing the herald patch approximately two weeks prior to the widespread eruption." — Outpatient consultation note