[Verification of the diagnosis of supratentorial ependymomas by real-time PCR].

Background: Differential diagnosis of supratentorial ependymomas is of particular difficulty in neurooncology due to nonspecific clinical and radiographic findings, a rare seen «classic» morphological picture, and a nonspecific immunophenotype. Thanks to molecular genetic methods, in particular real-time PCR, it has become possible to verify supratentorial ependymomas and identify their molecular group, on which further prognosis depends.

Objective: To develop a set of molecular genetic tests based on real-time PCR to verify supratentorial ependymomas.

Material and methods: 56 tissue samples were collected from patients with supratentorial ependymomas, WHO Grade II, and anaplastic ependymomas, WHO Grade III. We developed primers and fluorescent TaqMan probes for real-time PCR analysis to detect the ZFTA::RELA, ZFTA::MAML2, ZFTA::NCOA2, ZFTA::MAML3, YAP1::MAMLD1, and YAP1::FAM118B gene fusions. For immunohistochemical analysis, monoclonal rabbit anti-NF-kb p65 antibodies (HUABIO, China) were used, the study was carried out on AutostainerLink 48 immunostainer (DAKO, Denmark).

Results: Real-time PCR was able to verify the diagnosis for 69.9% (n=39) of samples and classify them into molecular groups of ZFTA- or YAP1-positive supratentorial ependymomas. Immunohistochemically it was possible to verify 58% (n=29) ependymomas.

Conclusion: Diagnosis by real-time PCR is a relatively fast, accessible and easily interpreted method that allows verification of the molecular group in 70% of cases of supratentorial ependymomas without the use of additional methods.