Highlights of changes in the International Consensus Classification of small B-cell lymphoid neoplasms
| Entity/category . | Change . |
|---|---|
| Chronic lymphocytic leukemia | Need to evaluate IGHV mutational status and TP53/17p alterations at the time of treatment. Reversible Richter-like proliferations in patients in which a BTK inhibitor has been interrupted must be distinguished from diffuse large B-cell lymphoma transformation. |
| Lymphoplasmacytic lymphoma (Waldenström macroglobulinemia) | Diagnosis may be made with lymphoplasmacytic aggregates in trephine biopsies <10% of cellularity with evidence of clonal B cells and plasma cells. Molecular studies for MYD88L265P and CXCR4 mutations are strongly encouraged in the workup of suspected lymphoplasmacytic lymphoma. |
| MGUS | Two types of IgM MGUS are recognized: a plasma cell type and an NOS type. Monoclonal gammopathy of renal significance and monoclonal gammopathy of clinical significance are recognized but they do not represent separate disease entities. |
| Primary cold agglutinin disease | Recognized as a new distinct entity. MYD88L265P mutation is absent. |
| Multiple myeloma | The term “multiple myeloma” is preferred over “plasma cell myeloma.” Multiple myeloma should be subclassified into 1 of 4 mutually exclusive cytogenetic groups (“multiple myeloma with recurrent cytogenetic abnormalities”) or designated as NOS. |
| Solitary plasmacytoma of bone and extraosseous plasmacytoma | Minimal bone marrow involvement by clonal plasma cells is of major prognostic importance, particularly with solitary plasmacytomas of bone. |
| Primary cutaneous marginal zone lymphoproliferative disorder | Now recognized as a distinct entity to be segregated from other mucosa-associated lymphoid tissue lymphomas and designated as a lymphoproliferative disorder. Two subtypes are distinguished largely based on expression of either class-switched Ig or IgM. |
| Follicular lymphoma | Cytological grades are maintained. In follicular lymphoma grade 3, BCL2 rearrangement and CD10 positivity both favor grade 3A over grade 3B. Patients with follicular lymphoma grade 3B with IRF4/MUM1 expression should be evaluated for IRF4 alteration, especially younger patients. Routine molecular testing is currently not required, but it can be useful in selected patients for differential diagnosis and specific therapeutic options (eg, EZH2 inhibitors). |
| BCL2-R negative, CD23-positive follicle center lymphoma | Recognized as a specific form of follicle center lymphoma, frequently but not always with a diffuse pattern, pelvic/inguinal location, and common STAT6 mutations. |
| Primary cutaneous follicle center lymphoma | Molecular and cytogenetic studies further support its segregation from other follicular lymphomas and may help predict subsequent extracutaneous dissemination. |
| Testicular follicular lymphoma | Recognized as a distinct form of follicular lymphoma in young boys. |
| Large B-cell lymphoma with IRF4 rearrangement | Upgraded to a definite entity. Occasionally identified in adults, and it has features similar to those in children. Definition does not include aggressive B-cell lymphomas with IRF4 rearrangements that may be associated with BCL2-R or MYC-R. |
| Mantle cell lymphoma | Definition is expanded to include genetic variants with CCND2 and CCND3 rearrangements with IG genes in otherwise typical mantle cell lymphoma. Aggressive B-cell lymphomas with secondary CCND1 rearrangements should not be diagnosed as mantle cell lymphoma. |
| Entity/category . | Change . |
|---|---|
| Chronic lymphocytic leukemia | Need to evaluate IGHV mutational status and TP53/17p alterations at the time of treatment. Reversible Richter-like proliferations in patients in which a BTK inhibitor has been interrupted must be distinguished from diffuse large B-cell lymphoma transformation. |
| Lymphoplasmacytic lymphoma (Waldenström macroglobulinemia) | Diagnosis may be made with lymphoplasmacytic aggregates in trephine biopsies <10% of cellularity with evidence of clonal B cells and plasma cells. Molecular studies for MYD88L265P and CXCR4 mutations are strongly encouraged in the workup of suspected lymphoplasmacytic lymphoma. |
| MGUS | Two types of IgM MGUS are recognized: a plasma cell type and an NOS type. Monoclonal gammopathy of renal significance and monoclonal gammopathy of clinical significance are recognized but they do not represent separate disease entities. |
| Primary cold agglutinin disease | Recognized as a new distinct entity. MYD88L265P mutation is absent. |
| Multiple myeloma | The term “multiple myeloma” is preferred over “plasma cell myeloma.” Multiple myeloma should be subclassified into 1 of 4 mutually exclusive cytogenetic groups (“multiple myeloma with recurrent cytogenetic abnormalities”) or designated as NOS. |
| Solitary plasmacytoma of bone and extraosseous plasmacytoma | Minimal bone marrow involvement by clonal plasma cells is of major prognostic importance, particularly with solitary plasmacytomas of bone. |
| Primary cutaneous marginal zone lymphoproliferative disorder | Now recognized as a distinct entity to be segregated from other mucosa-associated lymphoid tissue lymphomas and designated as a lymphoproliferative disorder. Two subtypes are distinguished largely based on expression of either class-switched Ig or IgM. |
| Follicular lymphoma | Cytological grades are maintained. In follicular lymphoma grade 3, BCL2 rearrangement and CD10 positivity both favor grade 3A over grade 3B. Patients with follicular lymphoma grade 3B with IRF4/MUM1 expression should be evaluated for IRF4 alteration, especially younger patients. Routine molecular testing is currently not required, but it can be useful in selected patients for differential diagnosis and specific therapeutic options (eg, EZH2 inhibitors). |
| BCL2-R negative, CD23-positive follicle center lymphoma | Recognized as a specific form of follicle center lymphoma, frequently but not always with a diffuse pattern, pelvic/inguinal location, and common STAT6 mutations. |
| Primary cutaneous follicle center lymphoma | Molecular and cytogenetic studies further support its segregation from other follicular lymphomas and may help predict subsequent extracutaneous dissemination. |
| Testicular follicular lymphoma | Recognized as a distinct form of follicular lymphoma in young boys. |
| Large B-cell lymphoma with IRF4 rearrangement | Upgraded to a definite entity. Occasionally identified in adults, and it has features similar to those in children. Definition does not include aggressive B-cell lymphomas with IRF4 rearrangements that may be associated with BCL2-R or MYC-R. |
| Mantle cell lymphoma | Definition is expanded to include genetic variants with CCND2 and CCND3 rearrangements with IG genes in otherwise typical mantle cell lymphoma. Aggressive B-cell lymphomas with secondary CCND1 rearrangements should not be diagnosed as mantle cell lymphoma. |