An unusual case of late recurrent adult granulosa cell tumor and mature teratoma arising within the same ovary, confirmed by NGS analysis.

Adult granulosa cell tumor is a predominant malignant tumor among ovarian sex cord-stromal tumors, representing approximately 3-5% of all ovarian malignancies and being known for its risk of recurrence with high mortality rate. We present a unique case of a 71-year-old woman with, to our knowledge, the first documented instance of a recurrent AGCT arising concurrently with a mature ovarian teratoma, confirmed through both immunohistochemistry and molecular biological analysis. The tumor in both the primary and recurrent lesion harbored a missense FOXL2 mutation typical for adult granulosa cell tumor. TP53, TSC2 and RB1 mutations were present only in the recurrent tumor, indicating secondary mutations acquired during progression.