Validation of tissue Microarray technology in malignant peripheral nerve sheath tumours

Karin Soares Gonçalves Cunha ^1*, Anabela Cunha Caruso ², Aline Soares Gonçalves ¹, Vagner Gonçalves Bernardo ¹, Andrea Cordovil Pires ¹, Eliene Carvalho da Fonseca ¹, Paulo Antônio Silvestre de Faria ², Licínio Esmeraldo da Silva ¹, Mauro Geller ³, Rodrigo Soares de Moura-Neto ⁴ and Vânia Silami Lopes ¹

¹ Universidade Federal Fluminense, Brazil
² National Institutes of Cancer (INCA), Brazil
³ Universidade Federal do Rio de Janeiro and UNIFESO, Brazil
⁴ Universidade Federal do Rio de Janeiro, Brazil

^* To whom correspondence should be addressed. E-mail: karingoncalves{at}terra.com.br.

Accepted 13 March 2009

Abstract

Aims: Because representativeness of the donor tissue cores used in tissue microarrays (TMAs) may be a disadvantage compared to full sections, the aim of this study was to validate the use of TMA technology in the study of malignant peripheral nerve sheath tumours (MPNSTs).

Methods: A TMA was constructed containing five independent core biopsies of 14 formalin-fixed, paraffin-embedded MPNSTs. The immunohistochemical (IHC) results of the five cores from the same tissue block on TMA were compared to the readings of whole-sections, using two antibodies: anti-Ki-67 and anti-S-100. Digital image analysis was performed to calculate the percentage of positive stain areas. The agreement between IHC results obtained with TMA cores and whole sections was assessed using the kappa statistic.

Results: There was good to very good agreement level between IHC results observed in whole and TMA sections from MPNSTs. In relation to S-100, we observed a very good agreement (92% of agreement; k= 0.77) using the minimum of four TMA cores. Staining results for Ki-67 from at least four readable TMA cores were the same as those of the whole section in 86% of cases, with a good agreement, using weighted kappa statistics (k=0.63).

Conclusions: Our study indicates that TMA technique can be used in the IHC study of MPNSTs, even using heterogeneous markers, such as S-100 protein.