BackgroundSex cord-stromal tumors with annular tubules are a rare tumor accounting for less than 1% of all ovarian malignancies. However, they are characterized by very late recurrence, which can be as late as 30 years after diagnosis and treatment.Case presentationA 16-year-old female Caucasian patient was treated in our department for a stage IA ovarian sex cord-stromal tumors with annular tubules. She underwent a left salpingo-oophorectomy and ipsilateral pelvic node biopsy with no adjuvant treatment. She was seen for amenorrhea after being lost to follow up for 16 years. The diagnosis of recurrence was made by radiology and the elevation of serum inhibin B level. The patient underwent resection of the tumor, left segmental colectomy, and paraaortic lymphadenectomy because the mass was massively adherent to the left mesocolon. Histology confirmed the diagnosis with no metastatic lymph nodes. No adjuvant therapy was indicated. The patient was lost to follow-up again for 4 years and re-presented for amenorrhea. Serum inhibin B level was high. A second recurrence was suggested, and the patient underwent a laparoscopic surgery. We performed left pelvic and paraaortic lymphadenectomy, and 3 months after surgery the patient was pregnant.ConclusionSex cord-stromal tumors with annular tubules is a slow-growing ovarian tumor with a high potential for recurrence and metastasis. Surgery is the mainstay of treatment. Due to the rarity of these tumors, they are often unsuspected and thus incompletely staged before primary surgery; the diagnosis is made by histological examination. The prognosis of these patients is unknown, and they require long-term follow-up.