Comparative evaluation of high-throughput small-core (0.6-mm) and large-core (2-mm) thyroid tissue microarray: is...

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Tissue microarrays (TMAs) are efficient for gene/protein expression profiling in large tumor cohorts.
• Previous studies suggest 0.6-mm cores approximate whole-section results, but colloid-rich tissues like thyroid may have fewer cells per core.
• Validating TMA core size and density is crucial for reliable thyroid cancer diagnostics.

Purpose of the Study:

• To validate thyroid TMAs using 0.6-mm and 2-mm core diameters.
• To assess the impact of core size and grid density on concordance with whole tissue sections.
• To evaluate the diagnostic accuracy of TMAs for thyroid carcinoma markers.

Main Methods:

• Construction of high-density (0.6-mm cores) and low-density (2-mm cores) TMAs.
• Immunohistochemistry using cytokeratin 19, HBME1, and CITED1 antibodies.
• Comparison of TMA results with whole tissue section analysis.

Main Results:

• High concordance between TMAs and whole sections for cytokeratin 19 (79-80%), HBME1 (95-92.8%), and CITED1 (89-98%).
• False negatives in TMAs were primarily due to focal, heterogeneous protein expression in whole sections.
• TMAs showed slightly lower sensitivity and higher specificity than whole sections, with similar overall accuracy (77-83%).

Conclusions:

• Focal/heterogeneous protein expression is the main cause of false negatives in thyroid TMAs.
• TMAs are accurate for screening protein expression in thyroid tissues, irrespective of core diameter or density.
• TMAs offer a reliable and accurate method for large-scale analysis of thyroid tissue biomarkers.