Prevalence of malignancy within cytologically indeterminate thyroid nodules

BACKGROUND: The optimal management of cytologically indeterminate thyroid nodules is controversial given the variable malignancy rates reported in this patient population. We examined the prevalence of malignancy within cytologically indeterminate follicular thyroid lesions in an attempt to predict malignancy based on cytologic features. METHODS: Cytopathology reports obtained after fine-needle aspiration biopsy (FNAB) examination of indeterminate follicular thyroid lesions were examined over a 4-year period. The prevalence of malignancy on final histology was determined in 4 indeterminate cytologic categories. RESULTS: A total of 107 records were available (91 women, 16 men). The mean patient age was 45.4 +/- 16 years. Forty-eight patients (45%) underwent surgery and had histopathologic diagnosis, while 57 patients did not have surgery. The prevalence of malignancy in patients who underwent thyroidectomy was 42% (20 of 48). CONCLUSIONS: The high prevalence of malignancy within indeterminate follicular lesions may necessitate thyroidectomy for patients with indeterminate follicular lesions on FNAB examination.