Table 1.
Differential diagnosis of ALK- ALCL and other hematopoietic tumors.
| Entity | Morphologic Features | CD30 | CD15 | CD4 | CD8 | Other T-Cell Markers: CD2, CD3, CD5, CD7 |
Cytotoxic Markers:Granzyme B, TIA-1, Perforin | MUM1 | ALK | PAX5 | EBER ISH | EMA, Other |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ALK- ALCL | Hallmark cells Pleomorphism Sinusoidal pattern May show starry-sky pattern DUSP22-rearranged: >Doughnut cells <Pleomorphism |
+ (>75% of cells) | Usually -rarely + |
Usually + | Usually - | Variable for all | Usually + except in DUSP22-rearranged cases | + | - | Usually -Very rarely + (PAX5 extracopies) |
- | Variable + EMA (40%) |
| ALK+ ALCL | Hallmark cells Pleomorphism Doughnut cells Sinusoidal pattern |
+ (>75% of cells) | - Very rarely + |
Usually + | Usually - | Variable for all | Usually + | + | + variable patterns |
Usually -Very rarely + (PAX5 extracopies) |
- | Usually + EMA (>80%) |
| Large cell PTCL, NOS | Usually no hallmark cells Variable pleomorphism | Variable <75% of cells | Usually -rarely + |
Variable | Variable | Variable | Usually - unless CD8+ |
Variable | - | - | - Rarely + |
- EMA If CD30+ difficult to distinguish from ALK- ALCL |
| CHL | Sclerosis and cellular nodules Polymorphic infiltrate Usually no hallmark cells Usually no sinusoidal patternSolid growth in syncytial variant |
+ | Usually + (60–70%) | Usually – Few + |
Usually – Few + |
Usually – Few variable |
Variable | + | - | Dim + | Variable NS-CHL (20%) MC-CHL (80%) |
- EMA |
| Anaplastic LBCL | Similar to ALCL, usually no hallmark cells May show sinusoidal pattern |
+ (30% of cases) | - | - | - | - | - | Variable | - unless ALK+ LBCL (cytoplasmic granular) |
+ Other B-cell markers + |
- unless EBV+ LBCL |
- EMA unless ALK+ LBCL B-cell markers variable or–in ALK+ LBCL |
| Myeloid/monocytic sarcoma |
Usually no hallmark cells Variable pleomorphism May show starry-sky pattern |
Usually - | + | + if monocytic | - | - | Variable | - | - | - + if t(8;21) |
- | - EMA + CD13, CD14, CD64, MPO, lysozyme |
| Histiocytic sarcoma | Usually no hallmark cells Variable pleomorphism Usually no sinusoidal pattern |
- | Variable | + | - | - | Variable | - | - | - | - | - EMA + monocyte/ macrophagemarkers CD68, CD163 |
Abbreviations: ALK: anaplastic lymphoma kinase; ALCL: anaplastic large cell lymphoma; EBER ISH: Epstein-Barr virus encoded RNA in situ hybridization; EMA: epithelial membrane antigen; PTCL, NOS: peripheral T-cell lymphoma, not otherwise specified; CHL: classic Hodgkin lymphoma; NS-CHL: nodular sclerosis CHL; MC-CHL: mixed cellularity CHL; LBCL; large B-cell lymphoma.