international neuroblastoma pathology classification: favorable histology group, patient less than 1.5 years of age, with poorly differentiated neuroblastoma (schwannian stroma-poor), and low or intermediate mitosis-karyorrhexis index
international neuroblastoma pathology classification: unfavorable histology group, patient of any age, with undifferentiated neuroblastoma (schwannian stroma-poor) and any mitosis-karyorrhexis index