MYCN amplification by Fluorescence in situ hybridization
(FISH):
FISH was performed either on smears (liquid-based preparation /
destained MGG stained smear) or on cell block section using Vysis LSI
N-MYC (2p24) spectrum green/ CEP 2 spectrum orange FISH probe (Abbott
Laboratories, USA) and visualized by Olympus BX-51 FISH imaging
system. A minimum of 100 nuclei were evaluated in all cases and
> 10 MYCN signals were taken as positive for
amplification. Ploidy was determined by counting the number of signals
with the CEP probe.