Pityriasis rosea hearald patch is on thigh for 3 and half months-why this long?only 2 other spots are present,they fade and back at other place.

Pityriasis rosea: Pityriasis rosea is an eruption thought to be of infectious etiology. 80% of cases remit spontaneously in 6-8 weeks. In refractory cases, ultraviolet light, systemic corticosteroids, or erythromycin for 2 weeks may be effective. However, a doctor visit is recommended to ensure that this is truly a recurrence, since that happens in less than 5% of cases by some reports.