Thyroid bed fine-needle aspiration: experience at a large tertiary care center.

Fine-needle aspiration (FNA) of thyroid bed (TB) lesions is a common diagnostic modality in monitoring patients for recurrent cancer after a thyroidectomy. To elucidate the value of TB FNA, we reviewed our experience at The Johns Hopkins Hospital, Baltimore, MD. We identified 57 TB FNA specimens from 50 patients. Of the patients, 36 were being followed up for papillary carcinoma, 7 for medullary carcinoma, 4 for follicular carcinoma (1 also had papillary carcinoma), and 1 for poorly differentiated neuroendocrine carcinoma; 3 had previous benign diagnoses. TB FNA yielded diagnostic material in 49 of 57 cases. Of 37 malignant or atypical FNA samples, 32 had surgical follow-up; 30 of 32 were confirmed malignant. The FNA result was benign in 12 of 57, including 6 cases of benign thyroid and 1 case of parathyroid tissue. Immunohistochemical staining was contributory in 5 of 57 cases. TB FNA is a highly reliable tool for diagnosing recurrent thyroid carcinoma. Residual benign thyroid and parathyroid tissue are potential pitfalls; awareness of these and judicious use of immunohistochemical staining can prevent misdiagnoses.