NCIt definition : Stage IV: Diffuse or disseminated involvement of one or more extralymphatic organs,
with or without associated lymph node involvement; or noncontiguous extralymphatic
organ involvement in conjunction with nodal stage II disease; or any extralymphatic
organ involvement in nodal stage III disease. Stage IV includes any involvement of
the CSF, bone marrow, liver, or lungs (other than by direct extension in stage IIE
disease). (from AJCC 8th Ed.);