Material and Method: Thirty-five primary neuroblastoma were evaluated. The data including stage, treatment protocol, metastatic disease, survival, N-myc status, age and prognostic categorization were obtained from the clinical records. The differentiation and MKI were evaluated in hematoxylin and eosin stained slides. Apoptotic activity was assessed by both bcl-2 immunohistochemical staining and the transferase-mediated d-UTP-biotin nick end labeling (TUNEL) method. Data were correlated with established prognostic factors and clinical outcome.

Results: Twenty-five (71.4%) cases were located in the adrenal. Sixteen cases showed low and 19 high MKI. Thirty-three (%94) were immunopositive for bcl-2. TUNEL staining was negative in 2 cases. Of the remaining positive 33 cases, 14 had an apoptotic index of ≤2%, 11 of 2-4% and 8 of ≥4%. Cases located in the adrenal showed higher scores of bcl-2 positivity than extra-adrenal tumors. There was no statistical significance for both bcl-2 staining and apoptotic index in correlation with cellular differentiation, MKI, N-myc amplification, age and other clinical parameters. Statistical significance was observed between bcl-2 scoring and tumor localization.