Microscopic examination of the biopsy specimen revealed histologic changes that are characteristic of common warts, including epidermal hyperplasia with compact hyperkeratosis, the presence of perinuclear vacuoles, and enlarged keratohyaline granules.
Common warts are caused by infection with human papillomavirus. In adults, they may occur at any place on the skin, but frequently develop on the hands, including the fingers, back of the hands, palms, interdigital spaces of the fingers, nail folds, and nail beds. The lesions vary in number and usually measure up to 3 to 5 mm in diameter.
Horny Excrescences on the Hands. Arch Dermatol. 2002;138(3):405-410. doi:10.1001/archderm.138.3.405