BACKGROUND Juvenile-type granulosa cell tumors (JGCTs) are a rare subtype of sex cord stromal tumor with a characteristic histology that is commonly found in the first 3 decades of life. It most commonly presents with symptoms of hyperestrogenism, which may present as precocious pseudopuberty or as menstruation-related symptoms, allowing for early detection of the tumor. CASE REPORT We present the case of a 12-year-old girl who presented to her primary care provider (PCP) with secondary amenorrhea with intermittent abdominal pain, who underwent an ultrasound for further evaluation, which revealed a large incidental pelvic mass. She was admitted to the Emergency Department (ED) and had findings of galactorrhea and hyperprolactinemia on examination. Imaging studies demonstrated a large ovarian mass measuring 15.0×9.0×18.8 cm that was resected, and subsequent pathology results showed JGCT stage 1A. CONCLUSIONS Prognosis of granulosa cell tumors (GCT) largely depends on its initial size, stage at diagnosis, residual tumors after surgery, and the subtype of GCT. If the patient is of reproductive age, fertility-sparing surgical options must be considered and patients must be regularly monitored for recurrence. JGCTs can present with minimal to no symptoms of precocious puberty in young girls but may present with amenorrhea, which may be considered normal for their developmental age. Although JGCTs are rare, they are important to include in differential diagnoses of younger female patients with abdominal pain, especially if accompanied by hormonal irregularities.