Risk of malignancy in non-diagnostic thyroid fine-needle aspiration biopsy in multinodular goitre patients.

Objective: Although the majority of biopsies is adequate for a cytological diagnosis, 5-20 % will be insufficient or nondiagnostic. Patients with nondiagnostic FNABs (ND-FNAB) may be further managed by continued observation, repeated FNAB, or thyroidectomy. The aim of this study was to determine the risk of malignancy in ND-FNAB, and to determine if there are any clinical factors that can be used to distinguish malignant versus benign disease in multinodular goitre patients with ND-FNAB.
Methods: A total of 411 multinodular goiter patients who underwent both a FNAB and thyroidectomy was the subject of study. Seventy nine of these patients with ND-FNAB were further reviewed retrospectively, and demographical and clinical factors were investigated to determine if there is any predictor of malignancy in this group of patients. Among these patients, FNAB has been repeated one more time in 5 (6.3 %) patients, and two more times in 9 (11.3 %) patients.
Results: Among 79 patients with ND-FNAB, 10 patients (12.6 %) had malignancy as found postoperatively. There were no differences in age, sex, functional status of the thyroid gland, and nodule size between patients with benign versus malignant disease.
Conclusion: Nondiagnostic FNAB remains a significant problem in the evaluation of thyroid nodules. Despite ultrasound guidance, clinicians should inform patients that there is a 5-15 % malignancy risk of initial nondiagnostic specimens.