Clinical outcomes for "suspicious" category in thyroid fine-needle aspiration biopsy: Patient's sex and nodule size are possible predictors of malignancy.

CONTEXT: Fine-needle aspiration (FNA) is recommended as an initial screening tool for the diagnosis of thyroid nodules. Approximately 10% of thyroid FNA diagnoses are "suspicious for neoplasm," warranting surgical resection.

OBJECTIVES: To examine the role of a patient's age, sex, size of nodule, and morphologic features as possible predictors of malignancy in patients with cytologic diagnosis of "suspicious for neoplasm."

DESIGN: Cytopathology slides and reports of 402 consecutive thyroid FNAs from 2000-2005 interpreted as "suspicious" were reviewed. Of these, 180 cases that had subsequent surgical resection were selected.

RESULTS: Of the 108 cases suspicious for follicular neoplasm on cytologic evaluation, histologic follow-up showed malignancy in 26 (24%). Of the 37 cases suspicious for Hürthle cell neoplasm, 15 (41%) had malignancy. Of the 35 cases suspicious for malignancy, 29 had malignant histologic diagnoses. Among cases with cytologic diagnoses of "suspicious for follicular or Hürthle cell neoplasm," the rate of malignancy in female patients was 22% as compared to 43% in male patients (P = .02). The rate of malignancy in nodules less than 2 cm was 19% compared to 47% in nodules measuring 2 cm or larger (P < .001). These differences were statistically significant. No statistically significant difference was noted between the age of the patient and the rate of benign versus malignant diagnosis.

CONCLUSIONS: Malignant tumors were more frequent in male patients with a cytologic diagnosis of "suspicious for follicular or Hürthle cell neoplasm" than in female patients. Risk of malignancy was higher in nodules measuring 2 cm or larger. Age of the patient was not a predictor of malignancy.