Neuroectodermal Rosettes in Immature Teratomas Are Not the Counterpart of Embryonal Tumours With Multilayered Rosettes.

BACKGROUND/AIM: Immature teratomas (IMT) are malignant germ cell tumours composed of immature embryonal tissue, mostly neuroectodermal tubules and rosettes. Meanwhile, embryonal tumours with multilayered rosettes (ETMR) are aggressive central nervous system tumours composed of neurocyte proliferation with rosette formation. The histopathological appearance of rosette formation in ETMR is the same as that in IMT. Recently, 19q13.42 amplification was reported as a specific genetic marker of ETMR. The aim of this study was to compare ETMR with IMT from histological, immunohistochemical and genetic perspectives. MATERIALS AND METHODS: We retrospectively analysed tumour samples from 48 patients with IMT and 1 patient with ETMR. We performed fluorescence in situ hybridization (FISH) analysis, which revealed amplification of the 19q13.42 locus in the ETMR case. In addition, immunohistochemical analyses of LIN28A, ß-catenin and p53 were performed. RESULTS: In FISH analysis all 48 cases of IMT showed diploidy. By immunohistochemical analysis, LIN28A expression was observed in 54% of IMT cases (25/48 cases) and in the ETMR case. Nuclear staining of ß-catenin was observed in 33% of IMT cases (16/48 cases). Meanwhile, aberrant expression of p53 was not identified in IMT nor ETMR cases. CONCLUSION: Genetic changes associated with IMT differ from those in ETMR, but LIN28A protein immunohistochemical expression, which is specific for ETMR, can be a biomarker for the immature neuroepithelial component in IMT.