Fibromatosis, or desmoid tumor, which is named for its hard tendonlike appearance, is a rare condition, with an estimated incidence of 2 to 4 cases per million patients per year.1,2A hereditary propensity toward abnormal connective tissue repair incited by trauma and growth response to sex steroid hormones has been proposed as a likely cause.3Approximately 10% to 15% of extra-abdominal desmoid tumors are located in the head and neck region. They are firm, locally invasive, usually well-differentiated overgrowths of fibrous tissue with a tendency to erode bone and soft tissue, putting vital structures in the head and neck area at risk.