A 10 year old female presented with a 3 week history of persistent vaginal bleeding, lower abdominal pain, and generalized fatigue. Further work-up determined that she had severe autoimmune hypothyroidism, precocious puberty, and a large left cystic ovarian mass, consistent with Van Wyk and Grumbach syndrome. In addition, the patient had elevated inhibin A and B levels, which may be elevated in granulosa cell tumor. The patient was managed with thyroid hormone replacement therapy and careful observation. Complete resolution of the ovarian mass and interval normalization of the inhibin levels were achieved. In females with severe primary hypothyroidism, ovarian masses, and elevated tumor markers, operative resection may be avoided with appropriate thyroid replacement therapy and close observation.