A 24-year-old woman presents to the gynecology clinic with complaints of progressive facial hair growth (hirsutism) and deepening of her voice over the past six months. She reports irregular menstrual cycles, with periods occurring every two to three months. Additionally, she has noticed mild pelvic discomfort and increased muscle mass in her arms and legs. She denies weight loss, fever, or a family history of hormonal disorders. Physical examination: Significant hirsutism on her face and chest Clitoromegaly Deepened voice Bimanual pelvic examination: A firm, non-tender, mobile adnexal mass measuring 5 cm is palpated on the right side Diagnostic findings: The mass is confirmed as a Sertoli-Leydig cell tumor of the right ovary. The patient has two living children and wishes to preserve her fertility. What is the primary treatment for a localized Sertoli-Leydig cell tumor in a young woman who wishes to preserve fertility?