2018-19 Section 7-Neoplastic and Inflammatory Diseases of the Head and Neck eBook

RD (95% CI)

Non-diagnostic Strickland

–0.08 (–0.21, 0.06) –0.01 (–0.16, 0.13) 0.00 (–0.18, 0.18) –0.04 (–0.12, 0.05)

Faquin Layfield Subtotal Benign Strickland Faquin Layfield Subtotal FLUS Strickland Faquin Layfield Subtotal

–0.08 (–0.14, –0.02) –0.04 (–0.07, 0.00) –0.04 (–0.14, 0.07) –0.04 (–0.07, –0.02) –0.18 (–0.30, –0.05) –0.14 (–0.20, –0.08) –0.02 (–0.13, 0.09) –0.11 (–0.19, –0.04) –0.08 (–0.22, 0.07) –0.15 (–0.22, –0.08) –0.02 (–0.15, 0.10) –0.10 (–0.18, –0.02) –0.41 (–0.54, –0.29) –0.23 (–0.33, –0.14) –0.17 (–0.39, 0.05) –0.29 (–0.43, –0.15) –0.05 (–0.09, –0.01) –0.03 (–0.05, –0.01) –0.13 (–0.24, –0.02) –0.05 (–0.08, –0.01)

Fig. 2. Forest plot of risk difference. It shows the risk difference for the rate of ma- lignancy for each category, as determined by the Bethesda System for Reporting Thy- roid Cytology. The risk difference is de- fined as the rate of malignancy using the new system (with the classification non-in- vasive follicular variant of papillary thyroid carcinoma, NIFTP) relative to the malig- nancy rate using the old system (without NIFTP). The boxes indicate point esti- mates for each study. The size of the box is proportional to the weight given to each study in the category average (subtotal). The whiskers indicate the 95% CI for the study estimate. Diamonds indicate the es- timated average. The length of the dia- mond is the 95% CI for the combined aver- age. FLUS, follicular lesion of undeter- mined significance; RD, risk difference.

Follicular neoplasm Strickland

Faquin Layfield Subtotal

Suspicious for malignancy Strickland

Faquin Layfield Subtotal Malignant Strickland Faquin Layfield Subtotal

–0.536

0

0.536

view found only 3 studies addressing this issue [10–12] . We also performed our own study of malignancy rates before and after the reclassification of some follicular variant papillary carcinomas of the thyroid to the benign NIFTP designation. The studies of Faquin et al. [10] , Strickland et al. [11] , Canberk et al. [12] and our own study examined a total of 9,796 FNAs of thyroid nodules. The results of this meta-analysis showed that the malig- nancy rates obtained using the new system (utilizing NIFTP) were significantly lower in 4 diagnostic catego- ries (Table 1). These categories were “benign,” “FLUS,” “follicular neoplasm,” and “suspicious for malignancy.” Use of the NIFTP category was not associated with a sta-

findings, in that many NIFTP nodules were diagnosed as AUS/FLUS or follicular lesion on FNA. However, in their series of 72 resected NIFTPs, approximately half were di- agnosed as suspicious for malignancy. They concluded that if lesions now designated as NIFTP were considered histologically benign, a significant change in the malig- nancy rate associated with indeterminate categories would occur [13] . We performed an extensive search of the published literature for studies addressing the impact on the malig- nancy rate of the original TBSRTC categories if some fol- licular variants of papillary thyroid carcinoma were re- classified as NIFTP (a benign lesion). Our literature re-

Layfield/Baloch/Esebua/Kannuswamy/ Schmidt

Acta Cytologica 2017;61:187–193 DOI: 10.1159/000469654

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