Twenty five thyroid tumors were investigated by immunohistochemistry for th
e presence of apoptosis, expression of p53, bax and bcl(2). In nine adenoma
s (average age 40) the rate of p53 positive cells was 5.7%, while it was 13
.3% for bax and 41.7% for bcl(2) in the tumor cells. In six follicular carc
inomas (average age 56) p53 positivity was obtained for 71.1%, while bax an
d bcl(2) positivity constituted 3.4 to and 2.5 to, respectively. In ten pap
illary adenocarcinomas (average age 42) p53 was positive in 39.6%, but bax
and bcl(2) were positive in 3.4% and 3% of the tumor cells, respectively. A
lmost no signs of spontaneous apoptosis were found in any of the cases. Det
ermination of p53, bax and bcl(2) ratio in thyroid tumors may contribute to
the differentiation between follicular adenomas and carcinomas.