Persistent pityriasis rosea: an unusual form of pityriasis rosea with persistent active HHV-6 and HHV-7 infection.

Pityriasis rosea (PR) is an acute, self-limiting exanthematous disease, associated with the reactivation of the human herpesvirus 6 (HHV-6) and/or human herpesvirus 7 (HHV-7) that usually lasts 6-8 weeks. We studied, from a clinical and virological point of view, 12 patients in whom the features of PR lasted longer than 12 weeks, defining this form of the disease as persistent PR (PPR). As in typical PR, in most of the PPR patients the disease begins with a herald patch, but compared to typical PR, systemic symptoms and oral lesions are more common. Moreover, in PPR we found a persistent reactivation of HHV-6 and/or HHV-7 with higher viral loads than in typical PR, accounting for the unusual persistence of the illness, the more frequent and severer systemic symptoms and the oral lesions. In conclusion, we describe an unusual persistent form of PR, whose prevalence has probably been underestimated so far and which should be added to the other variants of PR.