Giant breast tumors in a patient with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is an overgrowth disorder with increased risk of embryonal tumors, such as Wilms tumor, hepatoblastoma, neuroblastoma, and rhabdomyosarcoma. We report on a patient with BWS that developed a giant fibroadenoma of the breast that was surgically removed. The tumor relapsed 8 months after the surgery and the patient underwent partial mastectomy. Although the patient presented several clinical features of BWS, a molecular diagnosis was not achieved despite extensive molecular investigations on both blood and tumor tissue. A SNP array revealed a de novo 7p22.1 loss in both blood and breast tumor involving the mismatch repair gene PMS2 gene that may be potentially associated with the breast tumor. In conclusion, it remains unclear whether BWS patients have an increased risk of breast lesions or a yet unknown molecular defect is responsible for the rare occurrence of this tumor in BWS.