The distinction between warts and plantar calluses is sometimes difficult and is important because the latter can be treated with keratolytics and debridement alone and do not require the more destructive therapies used on verrucae. The difference can be determined by paring the lesion down with a scalpel blade. Warts will show a single or sometimes multiple cores that interrupt normal skin lines. They also exhibit dark red or black speckles, which are the thrombosed ends of the feeder vessels. Calloses show neither of these changes.
Basal Cell Carcinomas, Squamous Cell Carcinomas, and Keratoacanthoma
Large, keratotic VV that arise on sun exposed skin can simulate these nodular lesions. The differentiation can usually be made with a skin biopsy. The specimen should be read by a dermatologist or dermatopathologist.
Verrucous Carcinoma of Skin (Epithelioma Cuniculatum), and Squamous Cell Carcinoma of the Nail Bed
These rare lesions can simulate VV both clinically and histologically. The distinction is important because both are capable of metastasis. More often they cause local invasion which necessitates amputation or deforming surgery. Verrucous carcinomas are sizable fungating lesions, often on the soles. These should be referred to a dermatologist for management. Any subungual warty lesion that does not respond promptly to therapy should be referred to a dermatologist for evaluation. This is especially true in an adult patient or when there is a history of prior radiation exposure.
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