Assessment of fine needle aspiration cytology samples for molecular genetic analysis in neuroblastoma

To assess the utility of fine needle aspiration cytology (FNAC) samples for molecular genetic analysis of neuroblastoma.

The case files from the pediatric solid tumor clinic were reviewed to identify 20 neuroblastoma patients whose pre-treatment FNAC slides were preserved in the cytology laboratory. The FNAC slides were destained, air dried and hybridisation with fluorescence in situ hybridisation (FISH) probes was performed as per protocol. All slides were screened and analyzed carefully under the fluorescent microscope. Over four-fold increase of the N-myc signal numbers was defined as N-myc amplification. Focal occurrence of cells (at least 50) showing N-myc amplification surrounded by non-amplified tumor cells was defined as focal N-myc amplification. Presence of three or more signals for the long arm of chromosome 17 was defined as 17q gain.

FISH analysis gave informative results for all the FNAC smears in our study. FISH analysis of FNAC smears showed N-myc amplification in 5 (25 %) out of 20 patients and 15 (75 %) showed normal N-myc copy number. Three out of these five patients had homogenous amplification and two patients had focal N-myc amplification, indicating tumor heterogeneity. On investigation of chromosome 17q status, 5 (25 %) out of 20 patients demonstrated gain of 17q and 15 (75 %) patients showed normal 17q status. Four out of the five patients with 17q gain also showed N-myc amplification.

The current study indicates that FNAC is a rapid and atraumatic diagnostic method for neuroblastoma which provides sufficient material for molecular genetic analyses by means of FISH.