Abstract

Introduction: Tissue microarray (TMA) is a technology, which has come up in the recent years and has application in carrying out high throughput immunohistochemical and molecular analysis. The widespread use of this method in developing countries like India has been limited by the high cost of the automated tissue arrayers. The advantages of this technology has led researchers to find suitable and lesser expensive manual alternatives to creating such microarrays.

In this study, we used two such manual methods, described by Kononenet al¹ using prefabricated recipient blocks and the other by Chen et al² without the use of prefabricated recipient blocks, to manually create such microarrays. The aim of this study was to assess the efficacy of either or both the methods and also comparing the outcome differences in the preparation of standard H&E slides of cases of carcinoma breast. The idea was to propose the use of one technique over the other for routine immunohistochemistry in our set-up.

Materials and Methods: 65 cases of histologically confirmed carcinoma breast were included in the study.  Microarrays were constructed in a 5X3 grid using two manual methods, described by Kononenet al¹ and the other by Chen et al². Immunohistochemistry for HER-2, ER, PR and CK 5/6 were done on the TMA sections and compared with routine sections.  

Results: Both the methods for construction of TMA manually were found to be easy and economical for our setup. The use of tissue microarrays decreased the total staining time and also decreased the total amount of reagents used, decreasing the total expenditure. The Chen technique of TMA construction proved to be an easier technique to learn than the first.

Problems associated with the Kononen technique¹ were significant core loss and core mal-alignment, cores not being flushed to surface, broken cores and block cracking. Problems associated with the Chen technique²core tipping and cumbersome removal of adhesive tape.

There were averagely 20 sections obtained with almost all cores with the technique suggested by Chen et al,² on the other hand there were hardly any sections with all the cores with the technique suggested by Kononen et al.¹This could entail loss of assessment of one or the other tumor specimen or too few slides if all the cores were to be studied together.

Discussion: Therefore, if few slides are necessary, fewer specimens (20–30) have to be studied and
no precise arrangement is necessary then Kononen technique¹ is recommended. And if, many slides are necessary, there are few specimens (30–50) and precise arrangement is necessary, then Chen technique: TMA with double sided adhesive tape, is recommended.^2,3

Keywords: Tissue Microarray, Manual, Immunohistochemistry.