Derm Dx: A lesion on the lip

A 55-year-old man requests removal of a lesion affecting the vermilion border of his left lip commissure. The growth has been gradually enlarging in size over a one-year period and is asymptomatic. He denies prior history of verrucae and skin cancer; his father had a melanoma. He smokes cigarettes and is a social drinker. Examination reveals a 0.4 cm flesh-colored ...