Thyroid cytopathology: Bethesda and beyond

Thyroid nodules are commonly encountered in clinical practice. Although the overwhelming majority of them turn out to be benign, the small subset of cancerous nodules needs to be accurately identified for optimal and timely surgical management. Fine-needle aspiration has proven to be the most valuable diagnostic modality for pre-operative distinction of benign from malignant nodules. The recently introduced and much anticipated Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has standardized our diagnostic approach to reporting and cytomorphological criteria. TBSRTC has well-defined and rational management algorithms with implicit risk of malignancy in each of the 6 diagnostic categories. Recently published data supports the clinical utility and wide acceptance of TBSRTC by both practicing pathologists and clinicians. The problematic category of 'indeterminate' cytopathologic diagnoses has led to the discovery and development of unique and useful molecular markers, such as BRAF, which have displayed promising potential in recently published studies. As a result of the publication of TBSRTC, in 2009 the American Thyroid Association revised its clinical guidelines for the management of patients with thyroid disease and TBSRTC offers a useful source of information for the pathologist as well.