Derm Dx: A lip lesion and a history of basal cell carcinoma

A 62-year-old woman seeks consultation for a nonhealing lesion above her upper lip that has increased in size gradually over the past few months. Her medical history is positive for basal cell carcinoma of the right nares treated recently with radiation therapy. She is fair-skinned and quit smoking 5 years previously. Examination of the affected site reveals a crusted plaque ...