What is the starting lesion associated with pityriasis rosea called?

The starting lesion associated with pityriasis rosea is known as a herald patch. This initial lesion typically presents as a large, round, or oval patch with a slightly raised border and is often a single, solitary lesion that appears on the trunk or upper extremities. The herald patch is crucial in the diagnosis of pityriasis rosea, as it usually precedes the development of a widespread rash characterized by smaller, reddish-brown spots that follow a "Christmas tree" distribution on the back.

Recognizing the herald patch can facilitate early diagnosis and reassurance to patients, as pityriasis rosea is typically self-limiting and resolves spontaneously. Understanding the significance of this initial lesion helps in differentiating pityriasis rosea from other similar dermatological conditions, aiding clinicians in effective management.