Table 2.

Thyroid Core Needle Biopsy Results and Histologically Confirmed Diagnosis

CNB category	No.	Histologic confirmation	Benign	NIFTP	Malignant	ROM without NIFTP, %	ROM with NIFTP, %
I	39	9 (23.1)	4	0	5	13–56	13–56
II	841	28 (3.3)	25	1	2	0.2–7.1	0.4–10.7
III	17	4 (24)	3	0	1	6–25	6–25
IIIa	3	0	0	0	0	NA	NA
IIIb	6	3 (50)	2	0	1	17–33	17–33
IIIc	0	NA	NA	NA	NA	NA	NA
IIId	3	1 (33)	1	0	0	0	0
IIIe	5	0	0	0	0	NA	NA
IV	241	148 (61.4)	70	14	64	26.6–43.2	32.4–52.7
IVa	144	91 (63.2)	51	7	33	22.9–36.3	27.8–44.0
IVb	57	37 (65)	8	6	23	40–62	51–78
IVc	39	19 (49)	11	1	7	18–37	21–42
IVd	1	1 (100)	0	0	1	100	100
V	7	4 (57)	0	0	4	57–100	57–100
VI	236	236 (100)	0	0	236	100.0	100.0
Total	1,381	429 (31.1)	102	15	312	22.6–72.7	23.7–76.2

Values are expressed as number (%). The upper bound of the ROM was calculated by having all resected cases as denominator. The malignant cases (category VI) diagnosed by CNB were considered as histologically confirmed cases. The lower bound of ROM was calculated by having the total number of CNB cases as denominator.

CNB, core needle biopsy; NIFTP, noninvasive follicular thyroid neoplasm with papillary-like nuclear feature; ROM, risk of malignancy; NA, not available.