ABSTRACT
Purpose To analyze differential diagnosis between Hashimoto thyroiditis of atypical cell clusters ( ACC) and papillary thy-roid carcinoma (PTC). Methods 153 cases of Hashimoto thyroiditis (HT) were collected and divided into 3 groups:PTC group (49 cases), ACC group (32 cases), and HT as control group (72 cases). Morphology observations were done. CD56, CK19, galectin-3 and Ki-67 were detected by immunohistochemistry. Results Morphologic differences were observed among the groups. PTC showed milder positive expression of CK19 and galectin-3, and weaker positive expression of CD56 than that of ACC. Ki-67 index in ACC and PTC was lower than that of HT. Conclusions Morphological characteristics combined with CD56, CK19, Galectin-3 and Ki-67 evalu-ations could be valuable in the differential diagnosis between PTC and ACC.