Differential diagnosis of PBL
| . | PBL . | Plasmablastic myeloma . | LBCL HHV-8–positive . | IBL DLBLC . | ALK-positive DLBCL . | DLBCL ACI . | PEL . |
|---|---|---|---|---|---|---|---|
| Disease distribution | Extranodal | Bone marrow and extranodal | Nodal | Nodal | Nodal | Extranodal | Extranodal |
| HIV infection | ∼70% | No | Yes | No | No | No | Yes |
| Pathogenesis | EBV, HIV, IL-10 | IL-6 | HHV-8, MCD | ALK | EBV, IL-10, IL-6 | HHV-8 | |
| Positive markers | CD138, IRF-4/MUM-1, MYC | CD138, cytoplasmic Ig, MYC | CD20−/+, CD138+/−, IgM | CD20, PAX-5, | ALK, CD4, CD45 | CD20, CD4 | IRF-4/MUM-1, CD30−/+ |
| Negative markers | CD20, PAX-5 | CD20, PAX-5, BCL-6 | CD138 | CD4, CD138 | CD20, CD30, MYC | ALK | PAX-5, CD20, CD138, Ig |
| Proliferation rate | >90% | >90% | >90% | ∼80% | >90% | >90% | >90% |
| Cytoplasmic immunoglobulin | 50%-70% | >90% | IgA λ | Uncommon | Uncommon | Uncommon | Uncommon |
| EBV infection | Common | No | No | No | No | Common | Common |
| EBV latency pattern | I | NA | NA | NA | NA | III | I |
| HHV-8 infection | No | No | Yes | No | No | No | Yes |
| Molecular genetics | MYC GR | Myeloma FISH abnormalities | Unmutated Ig | MYC GR | t(2;17)(p23;q23) | TP53 mutations | Hypermutated Is |
| . | PBL . | Plasmablastic myeloma . | LBCL HHV-8–positive . | IBL DLBLC . | ALK-positive DLBCL . | DLBCL ACI . | PEL . |
|---|---|---|---|---|---|---|---|
| Disease distribution | Extranodal | Bone marrow and extranodal | Nodal | Nodal | Nodal | Extranodal | Extranodal |
| HIV infection | ∼70% | No | Yes | No | No | No | Yes |
| Pathogenesis | EBV, HIV, IL-10 | IL-6 | HHV-8, MCD | ALK | EBV, IL-10, IL-6 | HHV-8 | |
| Positive markers | CD138, IRF-4/MUM-1, MYC | CD138, cytoplasmic Ig, MYC | CD20−/+, CD138+/−, IgM | CD20, PAX-5, | ALK, CD4, CD45 | CD20, CD4 | IRF-4/MUM-1, CD30−/+ |
| Negative markers | CD20, PAX-5 | CD20, PAX-5, BCL-6 | CD138 | CD4, CD138 | CD20, CD30, MYC | ALK | PAX-5, CD20, CD138, Ig |
| Proliferation rate | >90% | >90% | >90% | ∼80% | >90% | >90% | >90% |
| Cytoplasmic immunoglobulin | 50%-70% | >90% | IgA λ | Uncommon | Uncommon | Uncommon | Uncommon |
| EBV infection | Common | No | No | No | No | Common | Common |
| EBV latency pattern | I | NA | NA | NA | NA | III | I |
| HHV-8 infection | No | No | Yes | No | No | No | Yes |
| Molecular genetics | MYC GR | Myeloma FISH abnormalities | Unmutated Ig | MYC GR | t(2;17)(p23;q23) | TP53 mutations | Hypermutated Is |
ACI, associated with chronic inflammation; ALK, anaplastic lymphoma kinase; FISH, fluorescence in situ hybridization; GR, gene rearrangement; IBL, immunoblastic; IL, interleukin; IRF-4/MUM-1, interferon regulatory factor 4/multiple myeloma 1; LBCL, large B-cell lymphoma; NA, not available; PEL, primary effusion lymphoma.