RESUMEN
To analyze the impact of cellular proliferative activity and apoptosis, MIB-1 immunopositivity and the apoptotic rate of normal tissue (n = 20), follicular adenoma (n = 30), follicular carcinoma (n = 32), papillary carcinoma (n = 40), Hashimoto thyroiditis (n = 17) and de Quervain thyroiditis (n = 12) was investigated by means of TV-image analysis. Three-micron sections from paraffin-embedded surgical specimens were investigated. Immunohistochemical reactions were performed using an indirect peroxidase method. For determination of apoptosis the in situ DNA nick-end labeling method (TUNEL) was used. The rate of positive cells was determined using the CM-2 TV-image analysis system (Hund, Wetzlar, Federal Republic of Germany). Forty viewing fields (1.94 mm2) were measured with 20:1 objective mangnification. An average of > 4,400 cells were assessed in each case. The mean MIB-1 immunopositivity was higher in follicular carcinoma (average, 2.30%) than in de Quervain thyroiditis (1.48%), papillary carcinoma (1.26%), Hashimoto thyroiditis (0.97%), follicular adenoma (0.58%) and normal thyroid tissue (0.14%). The apoptotic rates were higher in Hashimoto thyroiditis (4.54%) and de Quervain thyroiditis (3.55%) than in thyroid tumors (0.31%-0.49%) and normal thyroid tissue (0.10%). Calculating the ratio of MIB-1 expression and apoptotic rate, thyroid tumors (12.1-14.6) revealed higher values than normal thyroid tissue (3.6), indicating cell gain. In Hashimoto thyroiditis (1.7) and de Quervain thyroiditis (0.7) the ratio was lower than in normal tissue indicating cell loss. MIB-1 immunohistometry and apoptotic rate quantification present new insights into the proliferative and apoptotic potential of thyroid lesions based on a high number of cells investigated per case. The impact of both methods could be used for the interpretation of diagnostically difficult and inconclusive fine-needle aspirates. However, as there was an overlap of the single values, the results have to be interpreted carefully for diagnostic purposes.
