Rare metastatic patterns after malignant transformation of serous borderline tumor of the ovary.

Serous borderline tumors are rare, benign ovarian neoplasms that may recur and undergo malignant transformation to low-grade serous carcinomas (LGSCs). In this report, a 50-year-old female with a remote history of a serous borderline ovarian tumor experienced a recurrence of LGSC, presenting as a large solitary subcutaneous mass anterior to the sternum after a 33-year disease-free interval. The described case highlights the unpredictable nature of this disease and the importance of implementing lifelong surveillance strategies.