Unusual sites of extraskeletal metastases of Ewing sarcoma after allogeneic hematopoietic stem cell transplantation.

Allogeneic stem cell transplantation (SCT) for solid tumors remains under investigation. We report a case of extended disease stability after a nonmyeloablative peripheral blood SCT for metastatic, refractory Ewing sarcoma. Of note, the patient developed metastatic disease to 2 unusual sites-the brain and small intestine. The allogeneic SCT environment may alter typical metastatic patterns, and may represent an ideal platform to manipulate and enhance the antitumor immune response. Further clinical trials are needed to evaluate the role for allogeneic SCT for this disease.