Distribution of Extranodal Disease in Stage IV Patients
| No. of patients | |||
| Extranodal sites | Total | Single extranodal organ involved | ≥ 2 extranodal organs involved |
| Bone marrow only* | 23 | 23 | — |
| Soft tissue (non–bone marrow) only | 64 | 28 | 36 |
| Soft tissue and bone marrow† | 59 | — | 59 |
| Total | 146 | 51 | 95 |
↵* All cases for which bone marrow was identified as the only extranodal organ involved had marrow disease identified by PET but not by biopsy.
↵† All cases for which marrow biopsy histology was positive had at least one other, nonmarrow extranodal organ involved—that is, had at least 2 extranodal organs involved by lymphoma.