A rare case of recurrent phyllodes tumor of bilateral breasts with metastasis to the retroperitoneum and duodenum

Phyllodes tumors are uncommon fibroepithelial tumors of the breast. These tumors are graded based on the World Health Organization criteria into benign, borderline, and malignant subtypes. While benign phyllodes tumors are by far the most common presentation, borderline and malignant tumors have important clinical implications, as they are more likely to locally recur and metastasize. The most common sites of distant metastasis include the lung, bone, heart, and liver. Rare spread to the small intestines, kidney and pelvis have also been reported. We report a case of a 71-year-old woman with a history of locally recurrent phyllodes tumor of the breasts found to have retroperitoneal and intraperitoneal metastases. The retroperitoneal mass was just below the left kidney, extending into the pelvis, and overlying the psoas and iliacus muscle. The second mass involved the second portion of the duodenum, the proximal transverse colon, and the overlying mesentery. This is a rare case of delayed metastatic spread of phyllodes tumor to two sites, seventeen years after first presentation.