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Quantitative assessment of nuclear grooves in fine needle aspirates of the thyroid: a retrospective cytohistologic study of 94 cases.

OBJECTIVE
To quantify the association between the percentage of nuclear grooves and papillary thyroid carcinoma (PTC) in fine needle aspirates (FNAs) of the thyroid.


STUDY DESIGN
All the thyroid FNA cases (n = 1,775) received at the McGill University Health Center Cytopathology Laboratory in 2003 and 2004 were retrieved. The 94 diagnostic FNAs with histologic followup were selected. The percentage of nuclear grooves was quantified manually by counting the number of grooves in 300 cells, at x400, in the areas where the nuclear grooves were most frequent. Using descriptive statistics and graphs, we evaluated the association between the percentage of nuclear grooving and 2 outcomes of surgical diagnosis.


RESULTS
The mean percentage of nuclear grooves was 23.7% in PTC vs. 9.44% in non-PTC cases. We identified the cut-off of 20% nuclear grooving as having the optimal positive predictive value of 80% for presence of PTC and negative predictive value of 77% for absence of PTC.


CONCLUSION
The presence of nuclear grooves in > or = 20% of cells, as counted in selective fields where grooves are the most frequent, is highly predictive of PTC.