DNA Ploidy: Aneuploidy is linked to favorable outcome. A near-triploid DNA content due to whole chromosomal gains (no structural aberrations) has favorable prognosis. Diploid tumors tend to have unfavorable histology and are aggressive. Cytogenetic Alterations: Loss of 1p36 (seen in 25% to 35% cases) and 11q23, and gain of 17q21 are adverse prognostic factors. TRK gene expression: TRK gene codes for a nerve growth factor receptor and higher levels of expression are linked to favorable outcome. Urinary VMA/HVA Ratio: More primitive tumors lack dopamine beta-hydroxylase enzyme and show a VMA/HVA ratio of less than 1. Serum Tumor Markers: Increased serum levels of NSE, chromogranin A, ferritin, LDH, creatine kinase BB are linked to adverse outcome. Response to Treatment: In patients with high-risk disease, the extent of tumor shrinkage following induction chemotherapy predicts response to treatment. Persistence of neuroblastoma cells in the bone marrow after chemotherapy is an adverse prognostic indicator. The extent of decrease in mitotic activity and an increase in histologic differentiation also predict response to treatment. The image shows differentiating subtype of neuroblastoma. There is abundant neuropil and more than 5% of neuroblasts show differentiation towards ganglionic cells. Calcification is present in the fibrous septa.