OBJECTIVE: To study the expression of EpCAM and E-cadherin in papillary thyroid 
carcinoma and to analyze its correlation with various clinicopathologic 
parameters.
METHODS: Immunohistochemical study for EpCAM and E-cadherin was carried out in 
91 cases of papillary thyroid carcinoma. Twenty-four cases of papillary 
hyperplasia of thyroid were used as controls.
RESULTS: In all of the 24 cases of papillary hyperplasia, EpCAM was located on 
the cell membrane, while in the 91 cases of papillary thyroid carcinoma studied, 
EpCAM was located within the cytoplasm, with 36.3% (33/91) showing nuclear 
localization as well. In all the papillary hyperplasia cases studied, E-cadherin 
showed membranous expression. E-cadherin expression was reduced in 84.6% (77/91) 
of papillary thyroid carcinoma, as compared with the surrounding native thyroid 
parenchyma. Amongst the 33 cases of papillary thyroid carcinoma which showed 
nuclear localization of EpCAM, 30 cases also showed reduced E-cadherin 
expression. There was a positive correlation between nuclear expression of EpCAM 
and loss of E-cadherin expression (P = 0.000; Spearman correlation coefficient = 
0.857). Nuclear expression of EpCAM correlated with follicular variant of 
papillary thyroid carcinoma and presence of extrathyroidal extension ( P = 0.037 
and 0.033, respectively). Loss of E-cadherin expression correlated with age of 
patients and presence of lymph node metastasis (P = 0.018 and 0.010, 
respectively).
CONCLUSIONS: E-cadherin expression is reduced in papillary thyroid carcinoma, as 
compared with native thyroid parenchyma and papillary hyperplasia. Papillary 
thyroid carcinoma shows loss of EpCAM membranous expression and increased 
cytoplasmic/nuclear accumulation. Detection of these two markers may provide a 
valuable reference in defining the biologic behaviors of papillary thyroid 
carcinoma, including extrathyroidal extension and lymph node metastasis.