Tissue microarray technology used to assess EGFR status in human meningiomas
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Background : Large immunohistochemical studies on formalin fixed and paraffin embedded tissues requires sectioning and processing of many tumors, which is both expensive and time-consuming. Tissue microarray (TMA) technology allows for more efficient investigation of a large number of cases. However, the credibility of this procedure is not fully clarified for EGFR expression in human meningiomas. Aim : In this study we wanted to compare the immunostaining of EGFR on traditional whole tissue sections (WTS) with TMAs in these tumors. Methods : Two TMA blocks and their corresponding WTSs encompassing a total number of 47 cases were investigated using an EGFR antibody. The expression levels were recorded as a staining index (SI) and results from the two immunostainings were compared. Results : Significantly higher expression levels were found on WTSs compared with TMAs, however, the SIs were positively correlated. Further, some tumors regarded as negative on TMAs were positive on whole-tissue sections. Assessment of heterogeneous EGFR expression was also more indistinct on TMAs. Conclusion : The use of TMAs to assess EGFR receptor status in human meningiomas is encumbered with some degree of uncertainty, and thorough optimizing of the immunohistochemical procedure is required. With this in mind, TMA is an efficient method for immunohistochemical analyses of large tumor series.