Desmoid tumors are rare, soft-tissue neoplasms that do not metastasize, but exhibit aggressive growth and local invasion. They originate most frequently from abdominal fascial structures, although they can also appear at extra-abdominal sites. The most common extra-abdominal locations include the shoulder, chest wall, back, thigh, and head and neck. In children, desmoid tumors are more infiltrative, having a tendency towards osseous involvement more frequently than in adult patients. We report acase of a supraspinatus muscle desmoid tumor in a female patient with clavicle destruction.