2.6.4. Intravascular large B cell lymphoma

better understanding of MYC alterations in DLBCL. These are included in a new category of "High grade B cell lymphoma with MYC and BCL2 and/or BCL6 translocations". Co-expression of MYC and BCL2 is considered a new prognostic marker (double-expressor lymphoma). High grade lymphoma, NOS replaces B cell lymphoma unclassifiable (BCLU) category. It includes blastoid appearing large B cell lymphomas and cases lacking MYC and BCL2 or BCL6 that

Figure 3. Lymph node sections showing very aggressive DLBCL on immunohistochemistry. (a) bcl-2 positive (X20 magnification) (b) bcl-6 positive (X20 magnification) (c) ki 67 proliferation index is approximately 70-80% positive (X20

As the name suggests this variant is characterized by the predominance of infiltrating reactive T cells and macrophages (histiocytes). Presence of <10% cellularity, has been suggested to label this diagnosis. This pathological subtype does not appear to affect the outcome when adjusted for IPI. In a study of 40 patients comprising of predominantly middle-aged males, splenomegaly, bone marrow involvement, and hepatomegaly were present in 60, 43, and 40%, respectively [12]. The International Prognostic Index (IPI) (Table 3) was ≥2 in 77% of the patients. Tumor cells were uniformly positive for CD20 and negative for CD5, CD10, CD15, and CD138. Although these patients were relatively young, the use of combination chemotherapy, led to complete remission in only 40%, with an overall survival of 50% at 3 years. On multivariate analysis, only the IPI and deletions or point mutations in p53 were predictive of survival. In another study, the 5-year overall or event-free survival between this variant and DLBCL was

The tumor cells in plasmablastic lymphoma have large eccentrically placed nuclei, usually with single placed nucleoli and abundant basophilic cytoplasm. However these cells are distinct immunophenotypically. Instead of pan B cell markers which are present in typical DLBCL (CD 20, CD 79a), these tumors comprise of late B cell and express plasma cell markers like CD 138. MYC rearrangement is present in up to 50% of cases and 70% of these patients are Epstein-Barr virus (EBV) positive. Some tumors in this subtype are distinct genetically and clinically. For

would formerly have been called BCLU.

44 Hematology - Latest Research and Clinical Advances

magnification).

2.6.1. T cell histiocyte-rich large B cell lymphoma

not different among the IPI matched patients [13].

2.6.2. Plasmablastic lymphoma

2.6. Other distinctive clinicopathological subtypes of DLBCL

This is variously known as intravascular lymphomatosis, angiotropic large cell lymphoma, and malignant angioendotheliomatosis. It usually presents with disseminated intravascular proliferation of large lymphoid cells involving small blood vessels without an obvious extravascular tumor mass or leukemia. It commonly affects central nervous system, kidneys, lungs, and skin, but virtually any site may be involved.
