[Expression of cytokeratins and ret in thyroid papillary carcinoma]

To investigate the expression of cytokeratins and ret in thyroid papillary carcinoma (TPC) and their diagnostic value.

During the period of October 1999 to March 2002, 69 cases of TPC (42 cases with adjacent normal thyroid tissue) and 14 cases of nodular goiter with papillary hyperplasia were enrolled into the study. Immunohistochemistry for CK19, CK17, CK8, CK20 and ret was performed in all cases using EnVision and LSAB methods respectively.

The positive rates for CK19 and ret in TPCs were 85.5% and 68.1% respectively, which were significantly (P < 0.01) higher than those in nodular goiter and normal thyroid tissue (25.0% and 5.4% respectively). The expression of CK17 was also observed in a few cases of TPCs (11/69, 15.9%), which was mainly localized in areas of squamous metaplasia, poorly differentiated carcinoma and/or in the small infiltrative foci. The positive rates for CK8 were 75.4% and 26.8% in TPCs and benign thyroid tissue respectively. All cases were negative for CK20.

CK19, CK17 and ret expressions are significantly higher in TPCs than benign thyroid tissue; and this characteristic can have important diagnostic value.