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Practical diagnostic utility of thyroid fine-needle aspiration cell blocks: is always too much?
Jacob Edens1, Momal Chand1, Ishaq Asghar1
1Ascension St. John Hospital, Detroit, Michigan.
Insights
Cell blocks (CB) rarely aid thyroid fine-needle aspiration (tFNA) diagnoses and significantly increase turnaround time (TAT). Producing cell blocks only when needed can improve efficiency for thyroid nodule assessment.
Area of Science:
- Pathology
- Cytopathology
- Endocrinology
Background:
- Thyroid fine-needle aspiration (tFNA) is a primary method for evaluating thyroid nodules.
- Morphologic assessment of tFNA smears is generally accurate, but cell blocks (CB) can be used for ancillary studies like immunohistochemistry (IHC).
- Accurate and efficient cytologic diagnoses are crucial for guiding clinical decisions in thyroid nodule management.
Purpose of the Study:
- To evaluate the diagnostic utility of cell blocks (CB) in the assessment of thyroid fine-needle aspiration (tFNA) specimens.
- To determine the impact of CB preparation on the turnaround time (TAT) of tFNA diagnoses.
- To assess the contribution of CB to the final diagnosis and the need for ancillary studies.
Main Methods:
- Retrospective chart review of tFNA specimens from January 2014 to July 2019.
- Data collected included turnaround time (TAT), diagnosis, CB preparation, and diagnostic contribution of CB.
- Statistical analysis included descriptive statistics, the chi-squared test, and the Mann-Whitney U-test.
Main Results:
- Of 2321 tFNA specimens, 40.2% included a CB, but only 0.3% were diagnostically contributory.
- The median TAT for specimens with a CB was 1 day, compared to 0 days for those without a CB, representing a significant increase (P < 0.0001).
- Cases with CBs were significantly more likely to have a TAT greater than 1 day (65%) or 3 days (25.4%) compared to cases without CBs.
Conclusions:
- The diagnostic utility of cell blocks in tFNA for thyroid nodules is very low.
- The addition of a CB significantly increases turnaround time, delaying patient results.
- Producing CBs only when needed (e.g., for ambiguous smears or ancillary tests) can reduce TAT and resource utilization.
Introduction:
Thyroid fine-needle aspiration (tFNA) is a powerful screening tool for assessing solitary thyroid nodules. Generally, morphologic evaluation of smears yields an accurate diagnosis; but, in some cases it is useful to have a cell block (CB) to conduct ancillary studies such as immunohistochemistry (IHC). Cytologic diagnoses guide clinical decisions, so it is important that accurate and efficient diagnoses be rendered. Our study evaluates the diagnostic utility of the CB in the evaluation of tFNAs.
Materials And Methods:
We performed a retrospective chart review of all tFNA specimens from January 2014 to July 2019. Data collected included TAT (in days), diagnosis, if a CB was prepared, and if it was diagnostically contributory. Descriptive statistics were calculated. Data were analyzed using the χ2 test and the Mann-Whitney U-test.
Results:
Of the 2321 specimens, 40.2% (933) had CB and only 0.3% (7) were diagnostically contributory. IHC was used for 2 cases. For cases with CB, the median TAT was one day [0-18 days] and the median TAT without CB was 0 [0-9 days]. There was a significant difference in TAT between cases with a CB and those without. Most cases without a CB had same-day TAT (66.4%), whereas only 1.1% of those with a CB had same day TAT. Cases with CB were more likely to have a TAT >1 day (65% versus 12.1%) or >3 days (25.4% versus 10%) than those without a CB (P < 0.0001).
Conclusions:
We found the diagnostic utility of CB for tFNAs to be very low. The addition of a CB added at least 1 day to the TAT in all diagnostic strata. The additional time causes patients to wait for results, even for nondiagnostic studies. The increased TAT, resources, and manpower use may be reduced if CB were produced only as needed-if the results of the smear were ambiguous or if ancillary tests were needed to confirm the diagnosis.
