Review Question - QID 214912

A 36-year-old nulligravid woman presents to the clinic with 7 months of abnormal uterine bleeding. Her menstrual periods previously occurred regularly with only light cramping. For the past 7 months, she reports week-long bleeding in between her menstrual periods. She has no significant medical history and takes no medications. She is currently in a monogamous relationship and is interested in having children. Her temperature is 98.6°F (37.0°C), blood pressure is 115/70 mmHg, pulse is 70/min, and respirations are 12/min. Speculum examination shows normal vaginal and cervical mucosa without any lesions or ulcers, and the remainder of the physical exam is normal. A pelvic ultrasound demonstrates normal adnexa with a thickened endometrial stripe of 8 mm. Endometrial biopsy discloses endometrial hyperplasia with atypia. A urine pregnancy test is negative. Lab results are shown below:

Hemoglobin: 10.8 g/dL
Platelets: 180,000/mm^3
Urine beta-human chorionic gonadotropin (hCG): negative
Thyroid-stimulating hormone (TSH): 3.0 µU/mL
Prolactin: 10 ng/mL

Which of the following is the most appropriate next step in the management of this patient?