DIAGNOSTIC-VALUE OF DNA IMAGE CYTOMETRY AND P53 IMMUNOHISTOCHEMISTRY IN OXYPHILIC NEOPLASMS OF THE THYROID-GLAND

DNA image cytometry and immunohistochemistry with the anti-p53 antibody DO-1 has been performed in 30 oxyphilic adenomas and 15 well differentiated oxyphilic carcinomas of the thyroid gland in order to establish the value of these methods for the differential diagnosis of benign and malignant lesions of this tumor type. Aneuploidy was detected in 15 (50 %) oxyphilic adenomas and 12 (80 %) oxyphilic carcinomas (p < 0.05). Over-expression of p53 protein could be found in 4 (13 %) adenomas and 12 (80 %) carcinomas (p < 0.05). Additionally also, the quantification of p53 expression evaluating both the intensity of immunostaining and the number of cells with over-expression by means of an immunoreactivity score (IRS) showed significant differences (p < 0.05). There was no correlation of p53 over-expression and aneuploidy in the tumors examined. Our findings demonstrate a limited value of DNA image cytometry in the discrimination of benign and malignant oxyphilic neoplasms of the thyroid, since malignancy could not be excluded on the basis of this method. The high frequency of p53 over-expression in well differentiated oxyphilic carcinomas indicates, that this is an early event in the tumorigenesis of these tumors. The diagnostic value of p53 overexpression in the differential diagnosis of oxyphilic neoplasms of the thyroid is questionable.