Marginal zone B-cell lymphoma

Marginal Zone B-cell Lymphoma

Marginal Zone B-cell Lymphoma (MZL) is a type of non-Hodgkin lymphoma (NHL) that originates from B-cells in the marginal zone of lymphoid tissues. It is a heterogeneous group of indolent lymphomas that are generally slow-growing and can arise in various tissues, including the spleen, lymph nodes, and extranodal sites such as the stomach, salivary glands, and skin.

Classification

Marginal Zone B-cell Lymphoma is classified into three main subtypes:

• Extranodal Marginal Zone B-cell Lymphoma of Mucosa-associated Lymphoid Tissue (MALT lymphoma): This is the most common subtype and often occurs in the stomach, but can also be found in other mucosal sites such as the lungs, thyroid, and salivary glands.

• Nodal Marginal Zone B-cell Lymphoma: This subtype primarily affects the lymph nodes and is less common than MALT lymphoma.

• Splenic Marginal Zone B-cell Lymphoma: This subtype predominantly involves the spleen and often presents with splenomegaly and circulating lymphoma cells in the blood.

Pathophysiology

Marginal Zone B-cell Lymphomas are thought to arise from post-germinal center memory B-cells that reside in the marginal zone of secondary lymphoid follicles. These lymphomas are often associated with chronic inflammatory conditions or infections. For example, MALT lymphoma of the stomach is frequently associated with chronic infection by Helicobacter pylori.

Clinical Presentation

The clinical presentation of MZL varies depending on the subtype and site of involvement:

• MALT Lymphoma: Patients may present with symptoms related to the specific organ involved, such as dyspepsia or gastric bleeding in gastric MALT lymphoma.

• Nodal MZL: Patients may present with painless lymphadenopathy.

• Splenic MZL: Patients often present with splenomegaly and may have cytopenias due to hypersplenism.

Diagnosis

Diagnosis of MZL involves a combination of clinical evaluation, imaging studies, and histopathological examination of biopsy specimens. Immunophenotyping and molecular studies are often used to confirm the diagnosis and exclude other types of lymphomas.

Treatment

The treatment of MZL depends on the subtype and stage of the disease. Options may include:

• Antibiotic therapy: For gastric MALT lymphoma associated with H. pylori infection, eradication of the bacteria can lead to regression of the lymphoma.

• Radiation therapy: Localized MALT lymphoma may be treated with radiation.

• Chemotherapy and immunotherapy: Agents such as rituximab, alone or in combination with chemotherapy, are commonly used for more advanced or symptomatic disease.

• Splenectomy: This may be considered for symptomatic splenic MZL.

Prognosis

MZL is generally considered an indolent lymphoma with a favorable prognosis. However, the clinical course can vary, and some cases may transform into more aggressive forms of lymphoma.

Also see

• Non-Hodgkin Lymphoma
• B-cell Lymphoma
• Helicobacter pylori
• Lymphadenopathy