*6.7.1 Morphology and immunophenotype*

Burkitt Lymphoma shows diffuse infiltrate of intermediate-sized lymphoid cells with round or oval nuclei, coarse chromatin, several nucleoli, and a moderate amount of cytoplasm with high mitotic index and numerous apoptotic, cells the nuclear remnants of which are phagocytosed by interspersed benign macrophages. These phagocytes have abundant clear cytoplasm, creating a characteristic "starry sky" pattern. These are tumors of mature B cells that express surface IgM, CD19, CD20, CD10, and BCL6, and negative for BCL2 and Tdt. Ki 67 approaches nearly 100% [1, 25] (**Figure 7**).

### *6.7.2 Highlights in recent WHO classification*

• TCF3 (Transcription Factor 3) or ID3 (Inhibitor of DNA Binding 3), mutations in up to; 70% of cases [24, 57–61].

## *6.7.3 Burkitt-like lymphoma with 11q aberration*

• A new provisional entity that closely resembles Burkitt lymphoma but lacks MYC rearrangement and has some other distinctive features.

**61**

*B-Cell Lymphomas*

*DOI: http://dx.doi.org/10.5772/intechopen.87370*

*6.7.4 Treatment and prognosis*

**6.8 Diffuse large B-cell lymphoma**

*6.8.1 Morphology and immunophenotype*

multinucleated cells with large inclusion-like nucleoli.

older adults.

**Figure 7.**

Burkitt lymphoma is very aggressive but responds well to intensive chemotherapy. Most children and young adults can be cured. The outcome is more guarded in

DLBCL is molecularly heterogeneous. One frequent pathogenic event is dysregulation of BCL6. About 30% of DLBCLs contain various translocations that have in common a breakpoint in BCL6 at chromosome 3q27. Mutations are also seen in multiple other oncogenes including MYC and overexpression of the antiapoptotic protein BCL2. Tumors with BCL2 rearrangements usually lack BCL6 rearrangements. Co-expression of MYC with BCL2 and or BCL6 is now considered as double hit or triple hit lymphomas [1, 25, 63]. DLBCL typically presents as a rapidly enlarging mass at a nodal or extranodal site. Extranodal sites include the gastrointestinal tract, skin, bone, brain, and other tissues. Bone marrow involvement is relatively uncommon and usually occurs late in the course. Rarely, a leukemic picture emerges.

DLBCL usually shows a diffuse pattern of growth by a monotonous population of large cells that have a round or oval nucleus that appears vesicular due to margination of chromatin to the nuclear membrane, but large multilobated or cleaved nuclei are prominent in some cases. The cytoplasm is usually moderately abundant and may be pale or basophilic (**Figure 8**). More anaplastic tumors may even contain

DLBCL express CD19 and CD20 and show variable expression of germinal center B-cell markers such as CD10 and BCL6 and for markers IRF4 (interferon regulatory factor4) and MUM1 (melanoma associated antigen (mutated) 1) which classifies DLBCL into germinal center type and non-germinal center type. Cases with CD10 expression by >30% of cells are regarded as GC type as well as cases that are CD10−, BCL6+, IRF4/MUM1−. All other cases are regarded as of non-GC type [25, 62].

Diffuse large B-cell lymphoma (DLBCL) is the most common form of NHL. There is a slight male predominance. The median patient age is about

60 years, but can also occur in young adults and children.

*Burkitt lymphoma showing starry sky pattern with CD10 positivity and high Ki67.*

*Normal and Malignant B-Cell*

uncommon [1, 25].

**Figure 6.**

**6.7 Burkitt lymphoma**

*Lymphoplasmacytic lymphoma showing lambda restriction.*

with median survivals of 5–10 years. Transformation to large-cell lymphoma is

rapidly dividing lymphocytes. Less commonly, they have a leukemic phase. It is classified into (1) African (endemic) Burkitt lymphoma, (2) sporadic (nonendemic) Burkitt lymphoma, and (3) a subset of aggressive lymphomas occurring in individuals infected with HIV. Translocations of the MYC gene on chromosome 8 lead to increased MYC protein levels. The translocation partner for MYC is usually the IgH locus [t (8; 14)] but may also be the Ig κ [t (2; 8)] or λ [t (8; 22)] light chain loci. The translocated MYC allele often harbors additional point mutations. Endemic Burkitt lymphomas are seen to be latently infected with Epstein bar virus (EBV) (100%) and 20 to 40% in sporadic and immunodeficiency-associated Burkitt lymphomas. Both endemic and sporadic Burkitt lymphomas are found mainly in children or young adults. Most tumors involve extranodal sites. Endemic Burkitt lymphoma usually presents as mandibular mass and unusually involves abdominal viscera. In contrast, sporadic Burkitt

lymphoma often involves the ileocecum and peritoneum [1, 25, 57–59].

Burkitt Lymphoma shows diffuse infiltrate of intermediate-sized lymphoid cells with round or oval nuclei, coarse chromatin, several nucleoli, and a moderate amount of cytoplasm with high mitotic index and numerous apoptotic, cells the nuclear remnants of which are phagocytosed by interspersed benign macrophages. These phagocytes have abundant clear cytoplasm, creating a characteristic "starry sky" pattern. These are tumors of mature B cells that express surface IgM, CD19, CD20, CD10, and BCL6, and negative for BCL2 and Tdt. Ki 67 approaches nearly 100% [1, 25] (**Figure 7**).

• TCF3 (Transcription Factor 3) or ID3 (Inhibitor of DNA Binding 3), mutations

• A new provisional entity that closely resembles Burkitt lymphoma but lacks

MYC rearrangement and has some other distinctive features.

*6.7.1 Morphology and immunophenotype*

*6.7.2 Highlights in recent WHO classification*

in up to; 70% of cases [24, 57–61].

*6.7.3 Burkitt-like lymphoma with 11q aberration*

Burkitt Lymphoma is a high-grade B-cell lymphoma composed of medium-sized,

**60**

**Figure 7.** *Burkitt lymphoma showing starry sky pattern with CD10 positivity and high Ki67.*
