MYCN amplification and International Neuroblastoma Risk Group stratification on fine-needle aspiration biopsy and their correlation to survival in neuroblastoma

Aims Risk stratification as per the International Neuroblastoma Risk Group (INRG) stratification is important for management of neuroblastoma. INRG incorporates various parameters including histological category as per the International Neuroblastoma Pathology Classification (INPC) and MYCN amplification, which were evaluated in fine needle aspiration biopsy (FNAB) samples of neuroblastoma patients to ascertain their impact in our population. Methods This was a retrospective study including 60 neuroblastoma cases diagnosed on FNAB, staged and stratified by INRG. Mitosis Karyorrhexis Index (MKI), INPC morphological category and MYCN status by fluorescence in situ hybridisation (n=46) were evaluated and correlated to outcome. Results The mean age was 29 months (21 days to 9 years) with 27 and 33 children </>= 18 months; male: female ratio of 1.6: 1; INRG stage-30(M), 20(L2), 2(L1) and 2(MS); INRG-36 high-risk, 13 intermediate-risk and 11 low-risk categories, respectively. MKI was high, intermediate and low in 39, 4 and 7 cases, respectively. INPC morphological type included 2 ganglioneuroblastomas and 58 neuroblastomas, graded further as 25 undifferentiated and 33 poorly differentiated tumours. MYCN was amplified in 48% (22/46) cases and correlated with undifferentiated morphology (p=0.01). At a mean follow-up of 469 (7-835) days, 22/50 were disease free and 28/50 had relapsed/died. The overall survival correlated with age (p=0.03), stage (p=0.01), INRG group (p=0.0001) and tumour grade (p=0.036). MYCN status independently did not correlate with age (p=0.5), INRG stage (p=0.2) and overall survival (p=0.4). Conclusion FNAB is a complete modality for diagnosing neuroblastoma and providing all information required for risk stratification as per INRG including MKI, MYCN amplification, INPC category. Our cohort with predominant high-risk neuroblastoma cases highlights regional variation.