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 5 years or older, with any subtype of neuroblastoma (schwannian stroma-poor) and any mitosis-karyorrhexis index