Classification of myeloid malignancies
| FAB | WHO |
| Chronic myeloproliferative diseases | Chronic myeloproliferative diseases |
| Myelodysplastic/myeloproliferative diseases | |
| Myelodysplastic syndromes | Myelodysplastic syndromes |
| Acute myeloid leukamias | Acute myeloid leukemias |
The WHO classification system puts a few diseases that show characteristics of both myeloproliferative and myelodysplastic conditions into a new, separate group (myeloproliferative/myelodysplastic diseases).
Chronic myeloproliferative diseases (MPD)
Malignant stem cell disorder of clonal origin with a chronic course. It is characterized by splenomegaly and an elevated cell count in one or more cell lines. The marrow is hypercellular with signs of differentiation, there is no dysplasia.
| Classification of chronic myeloproliferative diseases | |
|---|---|
| FAB | WHO |
| Chronic myelogenous leukemia (CML) | CML Ph+: t(9;22)(qq34;q11), BCR/ABL |
| Chronic neutrophilic leukemia | |
| Agnogenic myeloid metaplasia with myelofibrosis (MF) (Idiopathic myelofibrosis) |
Chronic eosinophilic leukemia/hypereosinophilic syndrome |
| Polycythemia vera (EV) | Chronic idiopathic myelofibrosis |
| Essential thrombocytemia (ET) | Polycythemia vera |
| Essential thrombocytemia | |
CML
The most important change is that only the Ph+ cases are called CML by the WHO. The Ph- cases (which show myelodysplastic signs and are known to have significantly worse prognosis) are called aCML (atypical CML) and belong to the newly created myelodysplastic/myeloproliferative group. The CML term is somewhat misleading, because it is not CML at all, but was kept having no better alternative.
Myelodysplastic/myeloproliferative diseases
| WHO: myelodysplastic/myeloproliferative diseases |
|---|
| Atypical myelogenous leukemia (aCML) |
| Chronic myelomonocytic leukemia (CMML) |
| Juvenile myelomonocytic leukemia (JMML) |
CMML belonged to the MDS in the FAB classification. About one half of the cases show proliferative, the other dysplastic signs, but it appears that these are just different forms of the same disease.
Myelodysplastic syndromes (MDS)
| Myelodysplastic syndromes | |
|---|---|
| FAB classification of MDS | WHO classification of MDS |
| Refractory anemia (RA) | Refractory anemia |
| Refractory anemia with ringed sideroblasts (RARS) | with ringed sideroblasts (FAB: RARS) |
| without ringed sideroblasts (FAB: RA) | |
| Refractory anemia with excess blasts (RAEB) | Refractory anemia with excess blasts (FAB: RAEB) |
| Refractory anemia with excess blasts in transformation (RAEB-T) | |
| Chronic myelomonocytic leukemia (CMML) | Refractory cytopenia with multilineage dysplasia (new) |
| 5q- syndrome (new) | |
| unclassifiable (new) | |
Major changes: the RAEB-T of the FAB is now considered to be acute leukemia, not an MDS type.
CMML of the FAB was put into the new MPD/MDS group by the WHO.
A new group was formed from those cases previously classified as RA or RARS where the dysplasia affected more than one cell line, because the prognosis has been found worse for these cases (refractory cytopenia with multilineage dysplasia).
A new subgroup is 5q- syndrome (the loss of the long arm of chromosome 5).
Acute myeloid leukemias (AML)
| AML classification | ||
|---|---|---|
| FAB | WHO | |
| M0: minimally differentiated | AML with recurrent cytogenetic translocations | |
| M1: myeloblastic leukemia without maturation | AML with t(8;21)(q22;q22) AML1/CBFalpha/ETO | |
| M2: myeloblastic leukemia with maturation | Acute promyelocytic leukemia: AML with t(15;17)(q22;q12) and variants PML/RARalpha |
|
| M3: hypergranular promyelocytic leukemia | AML with abnormal bone marrow eosinophils inv(16)(p13;q22) vagy t(16;16)(p13;q22) CBFbeta/MYH1 |
|
| M4: myelomonocytic leukemia | AML with 11q23 MLL abnormalities | |
| M4Eo: variant, increase in marrow eosinophils | AML with multilineage dysplasia | |
| M5: monocytic leukemia | With prior MDS | |
| M6: erythroleukemia (DiGuglielmo’s disease) | Without prior MDS | |
| M7: megakaryoblastic leukemia | AML with myelodysplastic syndrome, therapy related | |
| Alkylating agent related | ||
| Epipodophyllotoxin related | ||
| Other types | ||
| AML not otherwise categorized | ||
| AML minimally differentiated | ||
| AML without maturation | ||
| AML with maturation | ||
| Acute myelomonocytic leukemia | ||
| Acute monocytic leukemia | ||
| Acute erythroid leukemia | ||
| Acute megakaryocytic leukemia | ||
| Acute basophilic leukemia | ||
| Acute panmyelosis with myelofibrosis | ||
The changes are easily summarized: the leukemias with consistent cytogenetic abnormalitites and those that are MDS related were taken into separate groups, the rest of the old FAB classification was put under the “AML not otherwise categorized” entry.
“REAL” classification of lymphoid malignancies
| WHO classification of lymphoid malignancies (part 1: non-Hodgkin types) | ||
|---|---|---|
| B cell | T cell | |
| Precursor B cell neoplasm | Precursor T cell neoplasm | |
| Precursor B lymphoblastic leukemia/lymphoma (precursor B cell acute lymphoblastic leukemia) |
Precursor T lymphoblastic lymphoma/leukemia (precursor T cell acute lymphoblastic leukemia) |
|
| Mature (peripheral) B cell neoplasms | Mature (peripheral) T cell neoplasms | |
| B cell chronic lymphocytic leukemia/small lymphocytic lymphoma | T cell prolymphocytic leukemia | |
| B cell prolymphocytic leukemia | T cell granular lymphocytic leukemia | |
| Lymphoplasmacytic lymphoma | Aggressive NK cell leukemia | |
| Splenic marginal zone B cell lymphoma (villous lymphocytes) | Adult T cell lymphoma/leukemia (HTLV-I+) | |
| Hairy cell leukemia | Extranodal NK/T cell lymphoma, nasal type | |
| Plasma cell myeloma/plasmacytoma | Enteropathy-type T cell lymphoma | |
| Extranodal marginal zone B cell lymphoma of MALT type | Hepatosplenic T cell lymphoma | |
| Mantle cell lymphoma | Subcutaneous panniculitis-like T cell lymphoma | |
| Follicular lymphoma | Mycosis fungoides/Sezary syndrome | |
| Nodal marginal zone B cell lymphoma (monocytoid B cells) | Anaplastic large cell lymphoma, primary cutaneous type | |
| Diffuse large B cell lymphoma | Peripheral T cell lymphoma, not otherwise specified (NOS) | |
| Burkitt’s lymphoma/Burkitt cell leukemia | Angioimmunoblastic T cell lymphoma | |
| Anaplastic large cell lymphoma, primary systemic type | ||
| WHO classification of lymphoid malignancies (part 2: Hodgkin disease) |
|---|
| Nodular lymphocyte-predominant Hodgkin’s disease |
| Classical Hodgkin’s disease |
| Nodular sclerosis Hodgkin’s disease |
| Lymphocyte-rich classical Hodgkin’s disease |
| Mixed-cellularity Hodgkin’s disease |
| Lymphocyte-depletion Hodgkin’s disease |