Nondiagnostic

In general, the adequacy of a thyroid fine needle aspiration (FNA) specimen is defined by both the quantity and quality of the cellular and colloid components. Optimal specimens ensure a low false-negative rate. Diagnostic accuracy begins with adequate tissue. Cytologic criteria constituting diagnostic adequacy is a controversial area in thyroid FNA cytology, with no consensus on required numbers of cells. With some exceptions, The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) recommends a minimum of six groups of well-preserved, well-visualized follicular cells, with each group comprising at least ten cells, for an adequate sample (quantity). Additionally, the quality of the preparation, processing, and staining is integral to a correct interpretation. Thyroid preparations that are satisfactory for evaluation (quality) show cells that are well stained, well preserved, and easily visualized. Limiting factors such as obscuring elements, cellular clumping or distortion, or poor staining or preparation are documented in adequacy statements. “Unsatisfactory” is a term applied to the adequacy statement and is no longer considered synonymous with “Nondiagnostic.” An unsatisfactory specimen, by definition, contains no diagnostic information. “Nondiagnostic” is the sole descriptive term used as the diagnostic line in the third edition of TBSRTC. A specimen may be adequate for evaluation in terms of quality and yet be nondiagnostic. Nondiagnostic specimens include those that do not represent the target, have fewer than six groups of follicular cells, or consist of cyst fluid containing histiocytes but inadequate follicular cells. However, aspirates with only colloid may not meet the cellular requirement for adequacy but may be diagnostic of a benign (colloid) nodule. Needle placement and target sampling are enhanced with ultrasound guidance, which has become the standard of care in the management of thyroid lesions.