BackgroundFallopian tube serous adenofibromas are uncommon tumors of the female genital tract, only dozens of cases have ever been reported. Earlier study indicated that they might be derived from embryonic remnants of the Müllerian duct. Clinical presentation of these tumors is usually asymptomatic. Small cysts of 0.5–3 cm in diameter are mostly incidentally found at the fimbriae end, with coarse papillary excrescences lined by epithelial cells and connective tissue stroma without nuclear pleomorphism or mitosis.Case presentationA 23-year-old woman with normal secondary sexual characters and 46, XX karyotype, presented to the gynecology clinic complaining of irregular menstrual cycles. Laboratory studies reported unique discrepancy of hormone levels; anti-Müllerian hormone (AMH): 6.05 ng/mL (The normal range of AMH is 1.70–5.63 ng/mL in women aged under 35 years old), follicle stimulating hormone (FSH): 31.9 mIU/mL (reference range: 3.85–8.78, follicular phase; 4.54–22.51, ovulatory phase; 1.79–5.12, luteal phase; 16.74-113.59, menopause), and luteinizing hormone (LH): 52.0 mIU/mL (reference range: 2.12–10.89, follicular phase; 19.18-103.03, ovulatory phase; 1.20-12.86, luteal phase; 10.87–58.64, menopause), mimicking gonadotropin-resistant ovary syndrome. The ultrasound reported a right adnexal cyst of 10.4 × 7.87 × 6.7 cm. Laparoscopic evaluation was performed; pathology revealed serous adenofibroma of the fallopian tube with ovarian stroma contents. Heterotopic extraovarian sex cord-stromal proliferations was most probable. The patient’s hormone levels returned to the reproductive status two weeks after surgery; FSH: 7.9 mIU/mL, LH: 3.59 mIU/mL,and AMH: 4.32 ng/mL. The patient’s menstrual cycles have resumed to normal for over two years after removal of the fallopian tube cyst.ConclusionsThis case of fallopian tube serous adenofibromas presented a discrepancy of serum AMH and FSH mimicking gonadotropin-resistant ovary syndrome. The clinical picture derived from heterotopic extraovarian sex cord-stromal proliferation indicated a disordered hypothalamus-pituitary-ovary axis.