A herald spot, also known as a herald patch, is the initial, often largest, lesion that appears on the skin in a condition called pityriasis rosea.
Here's a more detailed explanation:
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Definition: A herald spot is typically a single, oval-shaped, slightly raised, scaly patch on the skin that precedes the more widespread rash characteristic of pityriasis rosea.
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Appearance: It often appears as a pink or salmon-colored patch, sometimes with a slightly raised border. The scale is typically fine and may appear crinkled.
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Size: It can vary in size, but a herald patch is often larger than the subsequent rash spots. It can be up to 4 inches (10 centimeters) in diameter.
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Location: Common locations for the herald spot include the chest, abdomen, back, or face, although it can appear elsewhere on the body.
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Significance: The appearance of the herald spot is a key diagnostic feature of pityriasis rosea. While the exact cause of pityriasis rosea is unknown (though often linked to viral infections), the herald patch is usually the first visible sign of the condition before the characteristic "Christmas tree" pattern rash develops.
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Following Rash: About a week or two after the herald spot appears, smaller, similar spots erupt on the trunk, often arranged in an oval pattern resembling the branches of a pine tree.
In summary, a herald spot is the initial, relatively large skin lesion that marks the beginning of pityriasis rosea. It’s a distinctive sign that helps doctors diagnose the condition.
