Snapshot A 55-year-old man presents to his dermatologist for plantar warts. While the lesions do not hurt on its own, they are painful when he wears exercise sneakers or exercises. He reports that he has only one but is scared of it spreading. Physical exam reveals a single 3-mm flesh-colored papule with a thick scale. The striae of his plantar surface wind around the lesion. Cryotherapy is done in the office. Introduction Clinical definition cutaneous warts, or verrucae, are skin lesions caused by infection with human papillomaviruses (HPVs) common forms common warts (verruca vulgaris) flat warts (verruca plana) HPV type 3 and 10 plantar warts (verruca plantaris) HPV type 1 anogenital warts also known as condylomata acuminata HPV type 6 and 11 Epidemiology demographics children and young adults risk factors atopic dermatitis immunosuppression walking barefoot in communal swimming areas occupations handlers of meat and fish Etiology HPVs over 150 subtypes Pathogenesis transmitted through contact with infected skin of mucous membranes warts contain high viral load virus invades epidermal basal layer through microabrasions and are confined to epidermis incubation period is 2-6 months Prognosis often spontaneously resolves in children often require several sessions of treatment in adults Presentation Symptoms asymptomatic commonly appear at sites of trauma Physical exam commonwarts flesh-colored papules can be cauliflower-shaped smooth black dots (thrombosed capillaries) when pared with a surgical blade hands are most commonly involved flat warts pink, light brown, or light yellow flat-topped papules most commonly on mouth and forehead plantar warts on plantar surface of feet, often at points of maximum pressure accompanied with thick callus striae (natural lines of skin) often avoid the lesion single or grouped lesions warts on adjacent toes “kissing lesions” Studies Biopsy indications if diagnosis is unclear Histology epidermal hyperplasia hyperkeratosis koilocytosis Making the diagnosis a clinical diagnosis Differential Seborrheic keratosis “stuck on” appearance Acrochordon (skin tags) pedunculated Treatment Medical destruction of warts indications cosmetic reasons associated pain or irritation immunosuppression modalities topical salicylic acid first-line cryotherapy because of pain, usually used in older children or adults topical cantharidin laser topical immunotherapy indication refractory to first-line treatment modalities squaric acid dibutylester dinitrochlorobenzene (DNCB) diphenylcyclopropenone (DPCP) Complications No significant complications