Patients with an extraabdominal desmoid tumor have multiple minor bone abnormalities. The authors describe a rare case of an extraabdominal desmoid tumor that developed in a scar 2 years after surgery for Sprengel's deformity of the right shoulder in an 8-year-old girl. The association between the tumor and Sprengel's deformity has never been reported previously. Antecedent surgical trauma might play a role in the development of this tumor.