Sonographic findings in the surgical bed after thyroidectomy: comparison of recurrent tumors and nonrecurrent lesions.

OBJECTIVE: The purpose of this study was to assess the sonographic findings of recurrent tumors and nonrecurrent lesions mimicking recurrent tumors in the surgical bed after thyroidectomy for thyroid cancer.
METHODS: Fifty-eight patients who underwent sonography and sonographically guided fine-needle aspiration for evaluation of abnormal lesions in the surgical bed after thyroidectomy were included in this retrospective study. We compared the sonographic findings of recurrent tumors and nonrecurrent lesions, including lesion size, shape, margins, and echogenicity, presence or absence of microcalcification, and vascular flow signals. The reference standard was repeated sonographically guided fine-needle aspiration, surgery, or follow-up for at least 1 year.
RESULTS: Of 59 lesions in 58 patients, 20 were confirmed as recurrent tumors, and 36 were confirmed as nonrecurrent lesions in the surgical bed; 3 patients were lost to follow-up. On sonographic examination, the recurrent tumors diagnosed in 20 patients were oval in 70%, had well-defined margins in 100%, were hypoechoic in 70%, and had microcalcification in 10%. The average size was 0.7 cm (range, 0.4-2.1 cm). There was no statistical difference in sonographic findings between recurrent tumors and nonrecurrent lesions (P > .05). The 36 nonrecurrent lesions included remnant thyroidal tissue (n = 8), postoperative fibrosis (n = 7), suture granuloma (n = 7), strap muscle with a nodular contour (n = 4), reactive lymph nodes (n = 4), cysts (n = 3), tracheal cartilage (n = 2), and fat necrosis (n = 1).
CONCLUSIONS: For lesions located in the surgical bed in patients after thyroidectomy, the distinction between recurrent thyroid cancer and nonrecurrent benign lesions cannot be made on the basis of the sonographic features. Fine-needle aspiration is helpful in determining the histologic nature of such lesions.