Fibromatosis is a rare benign soft-tissue tumor of fibroblastic origin arising from the aponeurotic structures. Preoperative diagnosis of fibromatosis of the deep cervical fascia is difficult from clinical presentation alone. We report a case of a tumor of the cervical fascia space for which the radiologic appearance did not exhibit specific characteristics. Critical analysis of the radiologic images combined with fine-needle aspiration findings were helpful in suggesting preoperatively the diagnosis of fibromatosis, which was confirmed histologically after surgical resection.