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[297] Comparison between Conventional and Thin-Layer Cytology in Thyroid Lesions: Institutional Experience with 10,360 Cases

G Fadda, ED Rossi, A Mule', A Miraglia, CP Lombardi, CA Rota, FM Vecchio. Catholic University of Sacred Heart, Rome, Italy

Background: Fine needle aspiration biopsy (FNAB) represents the most reliable diagnostic tool in the diagnosis of thyroid lesions. The efficacy of thyroid cytology on FNAB processed by thin layer cytology (TLC) compared to conventional smears (CS) is evaluated in 3 reference periods based on the use of CS alone, both CS and TLC, and TLC alone.
Design: The efficacy of TLC alone compared to both TLC and CS in the same case and the CS alone in 10,360 thyroid lesions was evaluated in 3 reference periods. In the biennium 2004-2005, 4,522 FNABs were processed only with TLC, 3,442 had both CS and TLC in the period 2001-2002 and 2,396 only with CS in the period 1997-1998. These parameters of efficacy were chosen: rate of inadequacy (IR), rate of indeterminacy (INR) corresponding to the diagnosis of follicular neoplasm/lesion and rate of malignancy (MR).
Results: IR was 8.8% in 1997-1998, 18% in 2001-2002 and 13.1% in 2004-2005.MR was 2% in 1997-1998, 2.5% in 2001-2002 and 2.1% in 2004-2005. INR was 14.4% in 1997-1998, 21.4% in 2001-2002 and 14.5% in 2004-2005. The differences in IR in the earliest biennium compared to the following resides mainly in the fast check of the adequacy of CS slides done by the cytopathologists. The use of TLC and the increase of FNABs caused the discontinuation of adequacy control. The similarity of MR in all periods is an evidence of the diagnostic efficacy of TLC and CS.The trend of INR could be explained by the change of method (from CS to TLC) which reduces, at least in the training period, the self-confidence of the pathologist.
Conclusions: TLC alone decreases the number of both inadequate and indeterminate diagnoses without modifying the MR.The wide application of immunocytochemistry (ICC) on TLC may reduce the INR. The impossibility of the adequacy control during the FNAB suggests two passes for each lesion and the preparation of a second TLC slide in case of scant cell groups.
Category: Cytopathology

Monday, March 26, 2007 8:45 AM

Platform Session: Section E, Monday Morning