Differential diagnosis of warts includes the following: Corns (clavi): May obscure skin lines but do not have thrombosed capillaries when shaved Lichen planus: May mimic flat warts but may be accompanied by lacy oral lesions and Wickham striae and may be symmetrically distributed Seborrheic keratosis: May appear more stuck on, be pigmented, and include keratin-filled horn cysts Skin tags (achrocordon): May be pedunculated and smoother and more skin-colored than warts Squamous cell carcinoma: May be ulcerated, persistent, and grow irregularly DNA typing of the virus is available in some medical centers but is generally not needed.