Re-evaluation of epidermodysplasia verruciformis: Reconciling more than 90 years of debate.

Epidermodysplasia verruciformis (EV) is a rare genodermatosis characterized by abnormal susceptibility to cutaneous human beta-papillomavirus infections causing persistent flat warts or pityriasis versicolor-like lesions. This generalized verrucous skin disorder resembles generalized verrucosis, but these 2 conditions are distinguished by differences in clinical manifestation and the human papillomavirus types involved. A breakthrough in our understanding of EV was the discovery that homozygous inactivating mutations in TMC6 (EVER1) and TMC8 (EVER2) determine susceptibility to this disorder; however, they have not solved all EV cases fully. These deficiencies account for 75% of affected individuals, leaving a substantial number of patients without an underlying genetic cause. Recently, it has been revealed that mutations in additional genes (RHOH, MST-1, CORO1A, and IL-7) result in extensive human beta-papillomavirus replication and therefore manifest with an EV-like phenotype. The term "acquired EV" is used to describe an EV-like phenotype that develops in immunocompromised hosts, and the introduction of this entity further aggravates the confusion. Reevaluation of these entities is warranted. Here, we review the available data on this issue, provide up to date information on the major characteristics that differentiate between these seemingly clinically similar disorders, and highlight the different mechanisms involved in each disorder.