Pityriasis rubra pilaris with erythema gyratum repens-like eruption and resolution with ustekinumab.

Erythema gyratum repens (EGR) is a rare paraneoplastic disorder often preceding the diagnosis of underlying malignancy by 9 months on average, while pityriasis rubra pilaris (PRP) is an uncommon papulosquamous inflammatory disease. We present the case of a 58-year-old woman with an EGR-like eruption transforming from resolving PRP, without associated malignancy. Her rash dramatically resolved within a month of ustekinumab initiation, which supports this presentation as a unique entity.