Ewing's Sarcoma in a Patient with Crohn's Disease Treated with Ustekinumab: A Case Report

Biologic therapies have revolutionized the treatment of immune-mediated diseases. They are generally well tolerated; however, there are reports of malignancies associated with the use of these drugs. This case is of an adolescent with refractory Crohn's disease treated with ustekinumab, who subsequently developed Ewing's sarcoma. Patients treated with ustekinumab have reportedly developed B cell lymphoma, epithelioid sarcoma, as well as cancer of the lung, esophagus, ovary, testis, kidney, and thyroid. However, this is the first documented case of a patient treated with ustekinumab to develop Ewing sarcoma.