Assessing the Risk of False Negative Fine-Needle Aspiration Cytology and of Incidental Cancer in Nodular Goiter

Objective: In cases of multinodular goiter with negative cytological result, reasonable management options include surgical treatment, simple follow up, or more recently, conservative therapies like laser ablation, radiofrequency, or recombinant human TSH-augmented radioiodine (131I). In the case of patients who are eligible for follow up or non-surgical treatments, the possibility that they may be affected by an undiagnosed malignancy [false negative (FN) fineneedle aspiration cytology (FNAC) or by incidental thyroid cancer (ITC)] should be taken into account. The aim of our study was to assess the risk of malignancy in patients known to have presumably benign thyroid disease. Methods: Surgical series of patients who underwent total thyroidectomy for benign disease in 2000-2010 from two Italian centers were reviewed. Patients with any pre-operative suspicion of malignancy were excluded. Results: Eighty-four of 970 (8.6%) thyroidectomized patients revealed malignancy at histological exam (5% ITC, and 3.6% FN), with 89.8% of ITC having a diameter less than 10mm and 65.7% of FN having a diameter greater than 30mm. Sixty-seven of patients with thyroid malignancy (79.8%) had stage I disease (AJCC criteria). The risk of FN increases with increasing size of the nodule, while the risk of ITC increases as the size of the nodule decreases. Conclusions: The risk of malignancy in presumably benign thyroid disease can not be overlooked The risk of malignancy can be minimized through skilled ultrasound examination and FNAC. Once a patient with multinodular goiter is referred to follow up or non-surgical therapies, careful ultrasound surveillance is mandatory.