A 38-year-old woman undergoes cervical cytology screening. The Pap test shows atypical glandular cells (AGC). Colposcopy with endocervical curettage reveals the lesion marked **A** in the diagram — atypical endocervical glandular cells with preserved glandular architecture and an intact basement membrane with no stromal invasion. HPV testing is positive for HPV 18. Based on this histopathologic finding, which of the following is the most appropriate next management step?