Current State and Future Perspective of Molecular Diagnosis of Fine-Needle Aspiration Biopsy of Thyroid Nodules

Context: Fine-needle aspiration biopsy (FNAB) is the most sensitive and specific tool for the differential diagnosis of thyroid malignancy. Some limitations of FNAB can be overcome by the molecular analysis of FNAB. This review analyzes the current state and problems of the molecular analysis of FNAB as well as possible goals for increasing the diagnostic rate, especially in the indeterminate/follicular lesion cytological group. Evidence Acquisition: Twenty publications were evaluated for the diagnostic material and assay systems used, the type, and the number of mutations screened. Sensitivity, specificity, and false-negative and false-positive rates were calculated for all publications. Evidence Synthesis: Testing for a panel of somatic mutations is most promising to reduce the number of indeterminate FNAB. A mean sensitivity of 63.7% was achieved for indeterminate lesions. However, there is a broad sensitivity range for the investigation of mutations in the indeterminate lesions. Therefore, additional molecular markers should be defined by mRNA and microRNA expression studies and evaluated in FNAB samples of thyroid carcinomas without known somatic mutations, and especially for the many benign nodules in the indeterminate/follicular lesion fine-needle aspiration cytology category. This approach should improve the differential diagnosis of indeterminate/follicular lesion FNAB samples. Conclusion: Testing for a panel of somatic mutations has led to an improvement of sensitivity/specificity for indeterminate/follicular proliferation FNAB samples. Further methodological improvements, standardizations, and further molecular markers should soon lead to a broader application of molecular FNAB cytology for the differential diagnosis of thyroid nodules and to a substantial reduction of diagnostic surgeries.