Table 4. Receiver operating characteristic (ROC) curve analysis of Ep-ICD, EpEx and ESLI in thyroid tissues.

IHC Score	Differentiation of groups	AUC	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	p Value
Cytoplasmic Ep-ICD	PTC vs. Benign	0.893	76.7	87.5	98.6	24.6	<0.001
Cytoplasmic Ep-ICD	Aggressive vs. Non-aggressive PTC	0.739	84.3	38.7	72.9	55.8	<0.001
Nuclear Ep-ICD	PTC vs. Benign	0.735	51.6	87.5	97.9	13.6	0.002
Nuclear Ep-ICD	Aggressive vs. Non-aggressive PTC	0.841	70.2	83.9	89.5	59.0	<0.001
ESLI	PTC vs. Benign	0.900	84.8	68.8	96.9	28.2	<0.001
ESLI	Aggressive vs. Non-aggressive PTC	0.924	88.4	85.5	92.2	80.0	<0.001

The IHC score cut-off values for positivity were defined as ≥2 for nuclear Ep-ICD positivity; ≥5 for cytoplasmic Ep-ICD positivity and ≤5 for loss of membranous EpEx expression. ESLI cut-off ≥6 was used to determine ESLI positivity for distinguishing PTC from benign cases; and a cut-off value of >10 was used to determine ESLI positivity for distinguishing aggressive PTCs from non-aggressive PTCs.