Erythema gyratum repens associated with pityriasis rubra pilaris

Erythema gyratum repens (EGR) is a rare cutaneous eruption characterized by serpiginous morphology and a migrating scaly border. It is one of the most specific cutaneous paraneoplastic phenomena, and is associated with malignancy in most cases. We report a 46-year-old Afro-Caribbean man with the unequivocal clinical and histological features of pityriasis rubra pilaris (PRP). However, despite improvement on oral acitretin, the morphology of the eruption evolved into the striking serpiginous rash of EGR. The histology findings, although nonspecific, were in keeping with the diagnosis of EGR. No evidence of malignancy was found. Only four cases of PRP evolving into EGR have been reported in the literature, and none was associated with malignancy. All previously reported cases of EGR have been described in white patients, making our case the first reported exception, to our knowledge. The possible role of retinoids in altering the rash of PRP to that of EGR is discussed.