Medico

Molecular detection of lymphomas

The B-cell lymphomas are types of lymphoma affecting B cells.
B-cell lymphomas include both Hodgkin's lymphomas and most non Hodgkin.
They are often divided into indolent (slow-growing) lymphomas and aggressive lymphomas. Indolent lymphomas respond rapidly to treatment and are kept under control (in remission) with long-term survival of many years, but arenot cured. Aggressive lymphomas usually require intensive treatments, but have good prospects for a permanent cure.
Prognosis and treatment depends on the specific type of lymphoma as well as the stage and grade. Treatment includes radiation and chemotherapy. Early-stage indolent B-cell lymphomas can often be treated with radiation alone, with long-term non-reoccurrence. Early-stage aggressivedisease is treated with chemotherapy and often radiation, with a 70-90% cure rate. Late-stage indolent lymphomas are sometimes left untreated and monitored until they progress. Late-stage aggressive disease is treated with chemotherapy, with cure rates of over 70%.

Types

There are fourteen kinds of lymphomas involving B cells.
Five account for nearly three out of four patients with non-Hodgkinlymphoma:
• Diffuse large B cell lymphoma
• Follicular lymphoma
• Mucosa-Associated Lymphatic Tissue lymphoma (MALT)
• Small cell lymphocytic lymphoma (overlaps with Chronic lymphocytic leukemia)
• Mantle cell lymphoma (MCL)
The remaining nine are much less common:
• Burkitt lymphoma
• Mediastinal large B cell lymphoma
• Waldenström macroglobulinemia
•Nodal marginal zone B cell lymphoma (NMZL)
• Splenic marginal zone lymphoma (SMZL)
• Intravascular large B-cell lymphoma
• Primary effusion lymphoma
• Lymphomatoid granulomatosis
Additionally, some researchers separate out lymphomas that appear result from other immune system disorders, such as AIDS-related lymphoma.
Classic Hodgkin's lymphoma and nodular lymphocytepredominant Hodgkin's lymphoma are now considered forms of B-cell lymphoma.

Associated chromosomal translocations

Chromosomal translocations involving the immunoglobulin heavy locus (IGH) is a classic cytogenetic abnormality for many B-cell lymphomas, including follicular lymphoma, mantle cell lymphoma and Burkitt's lymphoma. In these cases, the immunoglobulin heavy locus forms a fusion protein withanother protein that has pro-proliferative or anti-apoptotic abilities. The enhancer element of the immunoglobulin heavy locus, which normally functions to make B cells produce massive production of antibodies, now induces massive transcription of the fusion protein, resulting in excessive pro-proliferative or anti-apoptotic effects on the B cells containing the fusion protein. In Burkitt'slymphoma and mantle cell lymphoma, the other protein in the fusion is c-myc (on chromosome 8) and cyclin D1 (on chromosome 11), respectively, which gives the fusion protein pro-proliferative ability. In follicular lymphoma, the fused protein is Bcl-2 (on chromosome 18), which gives the fusion protein anti-apoptotic abilities.
Burkitt´s lymphoma t(8,14) c-myc
Mantle cell lymphoma t(11,14) cyclinD1
Follicular lymphoma t(14,18) bcl-2
Follicular lymphoma is the most common of the indolent non-Hodgkin's lymphomas, and the second-most-common form of non-Hodgkin's lymphomas overall. It is defined as a lymphoma of follicle center B-cells (centrocytes and centroblasts), which has at least a partially follicular pattern. It is positive for the B-cell markers CD10, CD19, CD20, and CD22 butalmost always negative for CD5.
There are several synonymous and obsolete terms for this disease, such as CB/CC lymphoma (Centroblastic and Centrocytic lymphoma), nodular lymphoma and Brill-Symmers Disease.
A translocation between chromosome 14 and 18 results in the overexpression of the bcl-2 gene. As the bcl-2 protein is normally involved in preventing apoptosis, cells with an overexpression of...