B-cell lymphoma overview

# Overview
B-cell lymphomas make up most (about 85%) of the non-Hodgkin lymphomas (NHL) in the United States.  It develops more frequently in immunocompromised individuals (such as those with AIDS.)

# Classification
B-cell lymphomas include both Hodgkin's lymphomas and most Non-Hodgkins lymphomas. They are typically divided into low and high grade, typically corresponding to indolent (slow-growing) lymphomas and aggressive lymphomas, respectively. . The most commonly used classification system is the WHO classification, a convergence of more than one, older classification systems.

## Most common
Five account for nearly three out of four patients with non-Hodgkin lymphoma:
- 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)

## Rare
The remaining forms are much less common:
- Burkitt lymphoma
- Mediastinal large B cell lymphoma
- Waldenstrom macroglobulinemia
- Nodal marginal zone B cell lymphoma (NMZL)
- Splenic marginal zone lymphoma (SMZL)
- Extranodal marginal zone B cell lymphoma
- Intravascular large B cell lymphoma
- Primary effusion lymphoma
- Lymphomatoid granulomatosis
- T cell/histiocyte-rich large B-cell lymphoma
- Primary central nervous system lymphoma
- Primary cutaneous diffuse large B-cell lymphoma, leg type (Primary cutaneous DLBCL, leg type)
- EBV positive diffuse large B-cell lymphoma of the elderly
- Diffuse large B-cell lymphoma associated with inflammation
- Intravascular large B-cell lymphoma
- ALK-positive large B-cell lymphoma
- Plasmablastic lymphoma
- Large B-cell lymphoma arising in HHV8-associated multicentric Castleman's disease
- B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma
- B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and classical Hodgkin lymphoma

## Others
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 lymphocyte predominant Hodgkin's lymphoma are now considered forms of B-cell lymphoma.

# Pathophysiology

## Genetics
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 with another 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's lymphoma 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.

## Microscopic Pathology
Shown below is a microscopic image of Hodgkins Lymphoma which is a type of B cell lymphoma.Lymph node FNA specimen(Field's stain) The micrograph shows a mixture of  cells commonly seen in Hodgkins lymphoma:
- Eosinophils
- Reed Sternberg cells
- Plasma cells
- Histiocytes

# Treatment

## Medical Therapy
- Treatment includes radiation and chemotherapy.
- Early-stage indolent B-cell lymphomas can often be treated with radiation alone, with long-term non-recurrence.
- Early-stage aggressive disease 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%.