Criteria for Adequacy in Thyroid Fine-Needle Aspiration
Criteria for Adequacy in Thyroid Fine-Needle Aspiration
To determine whether some thyroid fine-needle aspirates classified as nondiagnostic correlate with benign thyroid nodules and can be distinguished from other nondiagnostic aspirates, I reviewed (from a total of 1,581) 80 nondiagnostic cases, all of which were hypocellular and lacked colloid, and correlated the cytologic findings with the results of pathologic follow-up.
Of the 80, 16 had carcinoma at follow-up and 64 were benign. The cellularity of the carcinoma cases ranged from 0 to 100 cells (mean, 20 cells), but every case with epithelial cells had Hürthle cell change or atypia suggestive of papillary carcinoma. The cellularity of the 64 benign cases ranged from 0 to 120 cells (mean, 40 cells), 17 of which had Hürthle cell change. There were 25 cases with at least 10 benign-appearing follicular cells without atypia or Hürthle cell change; all 25 cases were associated with benign follow-up.
While these results need to be confirmed by others, the evidence suggests that a proportion of thyroid aspirates that do not meet traditional criteria for adequacy still may be associated strongly with a benign thyroid nodule and can be distinguished from other nondiagnostic aspirates.
There are several different criteria for adequacy in thyroid aspirates. For lesions that lack abundant colloid (ie, colloid nodules), these include 6 groups each with 10 or more benign cells, 10 groups each with 20 or more cells, 6 groups on at least 2 of 6 aspirates, and 8 groups on at least 2 slides. Not surprisingly, the application of these criteria is not uniform, and in some reports as many as one third of cases diagnosed as adequate and benign were thought to be inadequate on review by other pathologists. Nevertheless, the very low false-negative rate in these large series demonstrates that these criteria do not often classify malignant cases as benign. However, there are few data addressing the converse, that is, whether these criteria classify some benign cases as nondiagnostic that can be distinguished from other nondiagnostic cases. To address this, I reviewed and correlated the cytologic findings of a large number of nondiagnostic cases with pathologic follow-up.
To determine whether some thyroid fine-needle aspirates classified as nondiagnostic correlate with benign thyroid nodules and can be distinguished from other nondiagnostic aspirates, I reviewed (from a total of 1,581) 80 nondiagnostic cases, all of which were hypocellular and lacked colloid, and correlated the cytologic findings with the results of pathologic follow-up.
Of the 80, 16 had carcinoma at follow-up and 64 were benign. The cellularity of the carcinoma cases ranged from 0 to 100 cells (mean, 20 cells), but every case with epithelial cells had Hürthle cell change or atypia suggestive of papillary carcinoma. The cellularity of the 64 benign cases ranged from 0 to 120 cells (mean, 40 cells), 17 of which had Hürthle cell change. There were 25 cases with at least 10 benign-appearing follicular cells without atypia or Hürthle cell change; all 25 cases were associated with benign follow-up.
While these results need to be confirmed by others, the evidence suggests that a proportion of thyroid aspirates that do not meet traditional criteria for adequacy still may be associated strongly with a benign thyroid nodule and can be distinguished from other nondiagnostic aspirates.
There are several different criteria for adequacy in thyroid aspirates. For lesions that lack abundant colloid (ie, colloid nodules), these include 6 groups each with 10 or more benign cells, 10 groups each with 20 or more cells, 6 groups on at least 2 of 6 aspirates, and 8 groups on at least 2 slides. Not surprisingly, the application of these criteria is not uniform, and in some reports as many as one third of cases diagnosed as adequate and benign were thought to be inadequate on review by other pathologists. Nevertheless, the very low false-negative rate in these large series demonstrates that these criteria do not often classify malignant cases as benign. However, there are few data addressing the converse, that is, whether these criteria classify some benign cases as nondiagnostic that can be distinguished from other nondiagnostic cases. To address this, I reviewed and correlated the cytologic findings of a large number of nondiagnostic cases with pathologic follow-up.
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