B-cell neoplasms
The largest group of lymphoproliferative disorders, which is conceptually divided into tumors derived from immature precursor cells and mature B-lymphocytes.
Precursor B-cell neoplasms include B-lymphoblastic leukemia/lymphoma. This form can be classified as NOS (NOS), or distinguished by the presence of specific genetic anomalies (e.g., BCR-ABL mutation).
Mature B-cell neoplasms are characterized by vast morphological diversity. Key nosologies:
- Chronic lymphocytic leukemia and small lymphocytic lymphoma.
- Diffuse large B-cell lymphoma (DLBCL). This is a heterogeneous group comprising germinal center B-cell and activated B-cell subtypes. Specific variants include: primary CNS DLBCL, cutaneous type (leg type), EBV-positive form, and chronic inflammation-associated forms.
- Follicular lymphoma (including a distinct pediatric type).
- Mantle cell lymphoma and marginal zone lymphoma (nodal, splenic, and extranodal MALT lymphoma).
- Highly aggressive tumors: Burkitt lymphoma, plasmablastic lymphoma, and unclassifiable B-cell lymphomas (with features intermediate between DLBCL and Hodgkin lymphoma).
- Plasma cell neoplasms: myeloma, Waldenström macroglobulinemia, various plasmacytomas.
T- and NK-cell neoplasms
Like B-cell neoplasms, they are classified by the maturation stage of the substrate. Precursor T- and NK-cell tumors are represented by the corresponding lymphoblastic leukemias/lymphomas.
The group of mature T- and NK-cell neoplasms frequently presents with extranodal involvement and specific clinical features:
- Skin involvement: Mycosis fungoides, Sézary syndrome, primary cutaneous CD30-positive disorders, and subcutaneous panniculitis-like T-cell lymphoma.
- Aggressive forms: Aggressive NK-cell leukemia, adult T-cell leukemia/lymphoma, hepatosplenic lymphoma, and extranodal NK/T-cell lymphoma (nasal type).
- Anaplastic lymphomas: Anaplastic large cell lymphoma (divided into ALK-positive and ALK-negative), including a rare breast implant-associated variant.
- Peripheral T-cell lymphoma, NOS (NOS) and angioimmunoblastic T-cell lymphoma.
Hodgkin lymphoma (HL)
The WHO classification strictly divides Hodgkin lymphoma into two biologically distinct groups:
- Nodular lymphocyte-predominant Hodgkin lymphoma — a distinct variant with a specific immunophenotype and clinical course.
- Classical Hodgkin lymphoma (Classical HL). Includes four histological subtypes:
- Nodular sclerosis
- Mixed cellularity
- Lymphocyte-rich
- Lymphocyte-depleted
Myeloid, histiocytic, and other neoplasms
In addition to lymphomas, the classification covers a wide range of hematopoietic tissue disorders:
- Myeloproliferative neoplasms: Chronic myeloid leukemia, polycythemia vera, primary myelofibrosis, essential thrombocythemia.
- Myelodysplastic syndromes (MDS): Conditions characterized by lineage dysplasia, ring sideroblasts, or excess blasts. Transitional forms are also distinguished — myelodysplastic/myeloproliferative neoplasms (e.g., chronic myelomonocytic leukemia).
- Acute myeloid leukemia (AML): Classified by genetic abnormalities, relationship to prior myelodysplasia, or therapy-relatedness. Myeloid sarcoma is also included here.
- Mastocytosis: Cutaneous, systemic, and mast cell leukemia.
- Histiocytic and dendritic cell neoplasms: Histiocytic sarcoma, Langerhans cell histiocytosis and sarcoma, Erdheim-Chester disease.
A separate category includes immune deficiency-associated lymphoproliferative disorders, such as post-transplant (PTLD) and other iatrogenic forms.
Briefly: answers to topical questions
What is the difference between nodular lymphocyte-predominant Hodgkin lymphoma and classical Hodgkin lymphoma?
Nodular lymphocyte-predominant Hodgkin lymphoma is a distinct disease entity that differs from the classical form in its pathogenesis and immunophenotype.
| Sign | Nodular lymphocyte-predominant HL | Classical HL |
|---|---|---|
| ICD-10 code | C81.0 | C81.1–C81.9 |
| Features | Independent type with a different pathogenesis and immunophenotype | Main type, includes several histological variants |
Classical Hodgkin lymphoma accounts for 95% of all cases and includes four histological types: nodular sclerosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted.
Which diseases belong to myelodysplastic/myeloproliferative neoplasms?
Myelodysplastic/myeloproliferative neoplasms include:
- chronic myelomonocytic leukemia;
- atypical chronic myeloid leukemia, BCR-ABL-negative;
- juvenile myelomonocytic leukemia;
- myelodysplastic/myeloproliferative neoplasms with ring sideroblasts and thrombocytosis;
- myelodysplastic/myeloproliferative neoplasms, unclassifiable.
To memorize the 4 variants of classical Hodgkin lymphoma, use the acronym NS, LR, MC, LD: Nodular sclerosis, Lymphocyte-rich, Mixed cellularity, Lymphocyte-depleted.
Class and exam questions
What do the abbreviations NOS/NOS mean in a diagnosis?
NOS (Not otherwise specified) means that the tumor belongs to a specific class (e.g., DLBCL) but lacks specific features to be classified into a narrower subtype.
How are B-cell and T-cell lymphomas classified?
The WHO classification is based on the distinction between precursor cell tumors (immature, e.g., lymphoblastic leukemias) and mature neoplasms (peripheral lymphomas).
Which viruses are identified as triggers in the lymphoma classification?
The classification explicitly outlines forms associated with the Epstein-Barr virus (EBV-positive DLBCL) and human herpesvirus 8 (HHV8-positive DLBCL).
What else to study on this topic
- Diagnostic criteria for various diffuse large B-cell lymphoma (DLBCL) subtypes
- Morphological differences between the 4 variants of classical Hodgkin lymphoma
- Genetic abnormalities in acute myeloid leukemia (AML)
- Classification of myelodysplastic syndromes (MDS)
- Post-transplant lymphoproliferative disorders (PTLD)
Master the entire topic in the "Diagnostic Radiology" course
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- Complete guide on the WHO Classification of Lymphomas and 2,199 more pages on the subject
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