Ewing Sarcoma in a Patient With Cowden Syndrome.

A 47-year-old woman, initially diagnosed in 1996 with Cowden syndrome (CS), PTEN-mutant bilateral breast cancer, a thyroid nodule, and uterine fibroids, presented to UCLA in 2013 with Ewing sarcoma of the pelvic bone. Her treatment course included mastectomies, hysterectomy/oophorectomy, and total thyroid resection, and chemotherapy, radiation, and hemipelvectomy for Ewing sarcoma. This case report illustrates the unusual presentation of Ewing sarcoma in a patient with PTEN-mutant CS, the probable underlying molecular pathogenesis, long-term management, and therapeutic considerations.