52) A 72-year-old man comes to OPD is evaluated due to a scaly | Dermatology

52) A 72-year-old man comes to OPD is evaluated due to a scaly lesion behind his right ear. A diagnosis of squamous cell carcinoma is confirmed on biopsy, and the patient undergoes excision of the lesion with clear margins. The wound is left to heal by secondary intention. Three weeks later, the patient returns to the office with a 2.5-cm raised, soft, granular lesion at the excision site. Biopsy of a representative lesion is shown in the image below:
Which is most likely responsible for this patient's postoperative changes?