Classification of non-Hodgkin lymphoma

What it is

The majority of non-Hodgkin lymphomas involve B cells, and a few are of T-cell lineage. Multiple lymph nodes are involved, extranodal involvement is common, and the spread is noncontiguous. The aggressive B cell lymphomas are set out one by one:

• Burkitt lymphoma: t(8;14) MYC-IGH, medium size lymphocytes, bone marrow infiltration with a starry sky histology, and one of the most rapidly growing malignancies, with a very fast doubling time.
• Diffuse large B-cell lymphoma, DLBCL: large B cells with a diffuse pattern of infiltration, aggressive disease, and it can present with primary CNS disease, PCNSL.
• Mantle cell lymphoma, MCL: small cells mostly, an intermediate to aggressive course of disease, t(11;14) IGH-CCND1, that is cyclin D1.

Beside the aggressive ones stand the indolent B cell lymphomas, and each carries a mark of its own.

• Chronic lymphocytic leukemia, CLL: the blood film shows monomorphic small lymphocytes with a soccer ball appearance and many smudge cells; there can be immune dysregulation, autoimmune hemolytic anemia and ITP; a TP53 mutation goes with lack of response to chemotherapy; and 5% undergo Richter's transformation to DLBCL.
• Follicular lymphoma: t(14;18) BCL2-IGH, small cleaved lymphocytes, and paratrabecular bone marrow infiltration.
• Lymphoplasmacytic lymphoma, that is Waldenstrom macroglobulinemia: MYD88 mutation, IgM paraproteinemia, and small plasmacytoid lymphocytes.
• Hairy cell leukemia: malignant lymphocytes in the blood with hairy projections, positive for the BRAF mutation.

So the codes sort the subtypes with nothing else needed: t(14;18) is follicular, t(8;14) is Burkitt and t(11;14) is mantle cell, while MYD88 is Waldenstrom and BRAF is hairy cell.