A 31-year-old man comes to the physician for a two-month history of a lesion on his left shin. It is not itchy or painful. Four years ago, he underwent a renal transplant due to rapidly progressive glomerulonephritis. Physical examination shows a 2×1-cm ulcerated, erythematous, crusted plaque on his left shin. Which of the following is the most likely diagnosis?
Actinic keratosis
Basal cell carcinoma
Contact dermatitis
Lichen planus
Molloscum contagiosum
Squamous cell carcinoma
