A 65-year-old man presents with multiple lesions on his penis that he has had for 2 months. Physical examination reveals shiny, soft, erythematous plaques on the glans and foreskin. Biopsy of lesional skin shows neoplastic epithelial cells, connected by intercellular bridges, with invasion into the dermis. Which of the following is the appropriate histologic diagnosis for this patient's penile neoplasm?
Adenocarcinoma Lichen planus Melanoma Squamous cell carcinoma