Subclassification of Follicular Neoplasms Recommended by the Japan Thyroid Association Reporting System of Thyroid Cytology

Table 2

Observer variability on 20 follicular pattern lesions by 4 reviewers.

Histological diagnoses	Reviewer
	A	B	C	D
AN	1	2	1	2
FA	1	1	1	1
FA	1	2	1	2
FA	1	2	1	2
FA	1	2	2	1
FA	2	1	1	2
FA	1	2	2	2
FA	2	2	2	2
FA	2	2	2	2
FA	3	2	2	2
FA	3	2	3	2
FA	2	3	2	3
FTC, minimally	1	2	1	2
FTC, minimally	1	2	1	2
FTC, minimally	2	2	2	2
FTC, minimally	3	2	3	2
FTC, widely	3	3	3	3
FTC, widely	3	3	3	3
PTC	1	2	1	1
PTC	2	3	2	3^*

Score 1: follicular neoplasm, favor benign; Score 2: follicular neoplasm, borderline; Score 3: follicular neoplasm, favor malignant; and Score 3^*: favor malignant but papillary carcinoma was suspected.
AN: adenomatous nodule; FA: follicular adenoma; FTC, minimally: follicular carcinoma, minimally invasive; FTC, widely: follicular carcinoma, widely invasive; and PTC: papillary carcinoma.