International Neuroblastoma Risk Group (INRG) Staging
L1 Localized tumor, not involving vital structures as defined by the list of imagedefined
risk factors (IDRF); confined to one body compartment.
L2 Loco regional tumor with presence of one or more IDRFs
M Distant metastatic disease
Ms Metastatic disease in children younger than 18 months with metastases confined
to skin, liver, and/or bone marrow (bone marrow involvement should be limited to
< 10% of total nucleated cells on smears or biopsy).