Medically reviewed by Jurairat J. Molina, MD A circular rash is commonly caused by a fungal infection called ringworm.

Pityriasis rosea (PR ... annular patch is the distinguishing hallmark of PR (see Figure 1). This herald patch is first noticeable as a small erythematous papule, but progresses into a round ...

Classically, pityriasis rosea begins as an erythematous, scaly patch on the trunk, known as a herald patch. This large lesion is commonly 2–10 cm in diameter, ovoid, erythematous and slightly ...