Herald Patch

Excerpt

A herald patch is a distinct skin manifestation characterized by a single, erythematous, round to oval scaly patch or plaque. The patch has a depressed center and raised border and measures 2 to 10 cm (see Image. Herald Patch). The lesion typically exhibits a predilection for the neck, chest, and back. As the lesion evolves, it tends to clear centrally, leaving the free edge of the scale. This reveals a unique "collarette" of scale, which is a common presenting sign of pityriasis rosea—a prevalent and self-limiting papulosquamous disorder. This clinical presentation resembles the edge of a cigarette paper directed inward toward the center.

The sign is called the "herald" patch or "mother" patch because it often appears a few days to 2 weeks before the complete eruption of pityriasis rosea. In 10% to 50% of the cases of pityriasis rosea, the herald patch may be absent, especially in drug-induced cases. On the other hand, the herald patch may appear in multiple locations and atypical sites, such as the soles or scalp. In some cases, the skin patch is the sole manifestation of the disease, not followed by a secondary rash.