Derm Dx: Swollen Lesion on the Lower Lip

A 63-year-old man presents for evaluation of a 5-day history of painful swelling affecting his lower lip. He denies antecedent trauma to the site. He does not have diabetes. He is a nonsmoker and drinks alcohol in moderation. Examination reveals an erythematous, 1.5-cm nodule that is tender to palpation. Cervical and submandibular lymph nodes are not palpable.

Can you diagnose this ...