Mahan Maazi, MEng, Faculty of Medicine, University of British Columbia.
Joseph M Lam, MD, FRCPC, Department of Pediatrics, Department of Dermatology and Skin Sciences, University of British Columbia, Vancouver, British Columbia, Canada.

Abstract
Cutaneous warts or verruca are benign growths of the skin that affect 30 to 70% of school-age children and has a lifetime prevalence of 10 to 22% in children. It is caused by human papillomavirus (HPV) which spreads from skin-to-skin contact or fomites and infects squamous cell in areas like the hands and feet. There are different HPV subtypes that cause different types of warts including common warts (verruca vulgaris), plantar warts (verruca plantaris), flat warts (verruca plana), mosaic warts, filiform/digitate warts, epidermodysplasia verruciformis, and condyloma acuminata (genital or venereal warts). Most warts will spontaneously clear within 2 years. Diagnosis is based on history and physical examination features which may include dermoscopy and rarely, histological confirmation. Management includes treatment with topical salicylic acid and cryotherapy, the two most common and effective modalities.
Key Words: warts (verruca), human papillomavirus (HPV), common warts (verruca vulgaris), plantar warts (verruca plantaris), flat warts (verruca plana), mosaic warts, filiform/digitate warts, epidermodysplasia verruciformis (EV), condyloma acuminata (genital or venereal warts).

Introduction
Warts or verrucae are caused by the human papillomavirus (HPV) which is a double-stranded DNA virus with over 200 distinct subtypes and is one of the most frequent viral mucocutaneous infections.¹ HPV can be transmitted through skin-to-skin or surface-to-skin contact and cause proliferation and growth of epidermal cells of the skin.^1,2,3 Warts are seen worldwide and can affect all age groups with a higher incidence in children and young adults and are rarely present before the age of 5.^1,2,4 Immunocompromised individuals are at an increased risk with higher incidence, resistant to treatment, and progression to intraepithelial neoplasms.^1,2 About 30% of warts will clear in 12 months and 60% clear in 24 months.^3,5 Different HPV subtypes can lead to different types and location of warts including common warts (verrucae vulgaris), plantar warts (verrucae plantaris), flat warts (verruca plana), mosaic warts, filiform/digitate warts, epidermodysplasia verruciformis, and condyloma acuminata (genital or venereal warts).^1,3,6 This paper will review warts including the various subtypes in the paediatric population.