Diagnostic key features that can be determined on BM evaluation in SLs
| Disease entity . | Neoplastic cell morphology . | Infiltration pattern . | Additional diagnostic clues . |
|---|---|---|---|
| SMZL | Small round lymphocytes and medium-sized cells with dispersed chromatin and pale cytoplasm | Intrasinusoidal with or without interstitial and nodular component | del(7q) in up to 40% of cases; surface IgM and IgD expression |
| SLL-u | |||
| SDRPBCL | Small- to medium-sized lymphocytes similar to those of SMZL | Intrasinusoidal | Frequent IgG surface expression; strong DBA-44 positivity |
| HCL-v | Medium-sized cells with oval or convoluted nuclei and prominent central nucleoli resembling prolymphocytes | Intrasinusoidal | Absence of significant reticulin fibrosis, annexin-A1 negative constant IgG surface expression |
| HCL | Small- to medium-sized lymphocytes with oval or indented nuclei, homogeneous chromatin and abundant cytoplasm | Loose interstitial or patchy | Specific annexin-A1 expression; increase in reticulin fibers |
| LPL | Small lymphocytes admixed with plasmacytoid lymphocytes and plasma cells | Nodular; interstitial or diffuse | Cytoplasmic Ig expression (mostly IgM); 6q- in up to 50% of BM-based cases; abundant mast cell infiltration |
| B-PLL | Medium-sized cell with round nucleus, moderately condensed chromatin, and prominent nucleolus | Interstitial; nodular | del(17p) in 50% of cases |
| MCL | Small- to medium-sized lymphoid cells with slightly to markedly irregular nuclei, dispersed chromatin, and inconspicuous nucleoli; blastoid variant shows larger cells resembling prolymphocytes | Dense interstitial; diffuse | t(11;14)/CCND1 rearrangement |
| FL | Small lymphocytes with slightly irregular nuclei and abundant pale cytoplasm. | Paratrabecular; nodular | t(14;18)/BCL2 rearrangement; BCL2 and BCL6 IHC expression |
| DLBCL | Neoplastic cells in the BM may be large or more frequently medium-sized lymphocytes resembling those of low-grade B cell lymphomas | Nodular; interstitial; diffuse | IRF4/MUM-1 IHC expression in up 65% of cases |
| MTLBL | Few scattered large B-cells intermingling with small T and B lymphocytes, and macrophages | Nodular; paratrabecular | |
| T-LGL | Large and granular lymphocytes with moderate to abundant cytoplasm and azurophilic ganules | Intrasinusoidal and interstitial | IHC expression of TIA-1, granzyme-B, and granzyme-M |
| HSTCL | Monotonous medium-sized cells with round nuclei and a rim of pale cytoplasm or atypical large cells with blastic morphology | Intrasinusoidal | Hyperplasia of the noninvolved marrow with or without dysplastic features; hemophagocytic histiocytosis |
| Disease entity . | Neoplastic cell morphology . | Infiltration pattern . | Additional diagnostic clues . |
|---|---|---|---|
| SMZL | Small round lymphocytes and medium-sized cells with dispersed chromatin and pale cytoplasm | Intrasinusoidal with or without interstitial and nodular component | del(7q) in up to 40% of cases; surface IgM and IgD expression |
| SLL-u | |||
| SDRPBCL | Small- to medium-sized lymphocytes similar to those of SMZL | Intrasinusoidal | Frequent IgG surface expression; strong DBA-44 positivity |
| HCL-v | Medium-sized cells with oval or convoluted nuclei and prominent central nucleoli resembling prolymphocytes | Intrasinusoidal | Absence of significant reticulin fibrosis, annexin-A1 negative constant IgG surface expression |
| HCL | Small- to medium-sized lymphocytes with oval or indented nuclei, homogeneous chromatin and abundant cytoplasm | Loose interstitial or patchy | Specific annexin-A1 expression; increase in reticulin fibers |
| LPL | Small lymphocytes admixed with plasmacytoid lymphocytes and plasma cells | Nodular; interstitial or diffuse | Cytoplasmic Ig expression (mostly IgM); 6q- in up to 50% of BM-based cases; abundant mast cell infiltration |
| B-PLL | Medium-sized cell with round nucleus, moderately condensed chromatin, and prominent nucleolus | Interstitial; nodular | del(17p) in 50% of cases |
| MCL | Small- to medium-sized lymphoid cells with slightly to markedly irregular nuclei, dispersed chromatin, and inconspicuous nucleoli; blastoid variant shows larger cells resembling prolymphocytes | Dense interstitial; diffuse | t(11;14)/CCND1 rearrangement |
| FL | Small lymphocytes with slightly irregular nuclei and abundant pale cytoplasm. | Paratrabecular; nodular | t(14;18)/BCL2 rearrangement; BCL2 and BCL6 IHC expression |
| DLBCL | Neoplastic cells in the BM may be large or more frequently medium-sized lymphocytes resembling those of low-grade B cell lymphomas | Nodular; interstitial; diffuse | IRF4/MUM-1 IHC expression in up 65% of cases |
| MTLBL | Few scattered large B-cells intermingling with small T and B lymphocytes, and macrophages | Nodular; paratrabecular | |
| T-LGL | Large and granular lymphocytes with moderate to abundant cytoplasm and azurophilic ganules | Intrasinusoidal and interstitial | IHC expression of TIA-1, granzyme-B, and granzyme-M |
| HSTCL | Monotonous medium-sized cells with round nuclei and a rim of pale cytoplasm or atypical large cells with blastic morphology | Intrasinusoidal | Hyperplasia of the noninvolved marrow with or without dysplastic features; hemophagocytic histiocytosis |
CCND1 indicates cyclin D1; IHC, immunohistochemistry; SDRPBCL, splenic diffuse red pulp B-cell lymphoma; HCL-v, hairy cell leukemia variant; and MTLBL, micronodular T-cell rich histiocyte-rich diffuse large B-cell lymphoma.