Recommendations for the management of cystic thyroid nodules

The management of cystic thyroid nodules has not been standardized with respect to an initial fine-needle aspiration cytology (FNAC) cystic change result, which is defined as fluid aspiration and a smear with numerous macrophages but scant or no follicular cells. In the present study the physical characteristics of cystic thyroid nodules predictive of the pathology were investigated, and recommendations made on their management.

The aspiration results of 1436 thyroid nodules managed between 1998 and 2000 were investigated. A total of 157 patients who had a subsequent operation or follow-up data with reaspiration were the subjects of the present study. Age, sex, nodule characteristics and others were examined as possible predictors of cancer risk.

The malignancy rate was 8.9%. Ten cases (71%) of malignancy were not cytologically diagnosed. Male sex and a nodule size of > or = 4 cm were found to be statistically significant predictors of malignancy. The malignancy rate was highest (100%) when a cystic lesion had malignant cytology on reaspiration and local invasion on radiology.

When a cystic change is observed by initial FNAC of thyroid nodules, nodules of > or = 4 cm must be reaspirated and a firm cytologic diagnosis made to rule out malignancy. Nodules should be considered for surgery having taken into account other characteristics, in particular male sex and radiologic findings of local invasion.