The INSS categorizes neuroblastoma into five stages:
Stage 1: Localized tumor confined to the area of origin, completely resectable. Stage 2A: Localized tumor with incomplete resection; no regional lymph node involvement. Stage 2B: Localized tumor with or without complete resection; regional lymph node involvement. Stage 3: Unresectable unilateral tumor infiltrating across the midline with or without regional lymph node involvement; or localized unilateral tumor with contralateral regional lymph node involvement. Stage 4: Any primary tumor with dissemination to distant lymph nodes, bone, bone marrow, liver, skin, and/or other organs (except as defined for stage 4S). Stage 4S: Localized primary tumor (as defined for stage 1, 2A, or 2B) with dissemination limited to skin, liver, and/or bone marrow (limited to infants younger than 1 year).
