international neuroblastoma pathology classification: favorable histology group, patient age 1.5 years up to but less than 5 years, with differentiating neuroblastoma (schwannian stroma-poor), and low mitosis-karyorrhexis index
international neuroblastoma pathology classification: unfavorable histology group, patient less than 1.5 years old, with poorly differentiated or differentiating neuroblastoma (schwannian stroma-poor) and high mitosis-karyorrhexis index