Nodal Marginal Zone B cell Lymphoma

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What is Nodal Marginal Zone B cell Lymphoma?

Lymphoma is divided into 2 broad groups: Hodgkin's lymphoma and non-Hodgkin's lymphoma. Non-Hodgkin's lymphoma has many subtypes - and one of them is Nodal Marginal Zone B-cell Lymphoma. As the name suggests, it primarily affects the B cells. Nodal marginal zone B-cell lymphoma is the nodal (i.e. happens in the lymph nodes) manifestation of MALT lymphoma (see other article on MALT lymphoma).

Lymphoma means cancer of the lymphatic system. The lymphatic system is important to our immune system where it helps to combat infection. The lymphatic system consists of several organs, e.g. lymph nodes, spleen, thymus and bone marrow, where all these are connected by tiny vessels. Lymphatic fluid is the medium that circulates in these tiny vessels. Like blood, it has cells in them. These cells can be divided into 2 types: T cells and B cells.

Who gets Nodal Marginal Zone B cell Lymphoma?

The following figures are according to the Australian Institute of Health and Welfare:

The incidence of non-Hodgkin's lymphoma is increasing over the years.

In 2001, the 3499 cases of non-Hodgkin's lymphoma were reported.

For non-Hodgkin's lymphoma, the male:female ratio is 1.22:1

In 2000, 2938 cases of B cell lymphoma (i.e. a subgroup of non-Hodgkin's lymphoma affecting primarily B lymphocytes) were reported in Australia. B cell lymphoma is the commonest subgroup of non-Hodgkin's lymphoma.

Nodal marginal zone B-cell lymphoma is a rare disorder. It represents 1% of all non-Hodgkin's lymphoma.

Predisposing Factors

The cause of nodal marginal zone B-cell lymphoma is not known. However, several risk factors in terms of age, sex and race are identified based on the statistics available.

Age: More commonly in middle aged to elderly people.

Sex: Females are affected slightly more than males, but overall male:female ratio of non-Hodgkin's lymphoma is 1.22:1 (see above)

Race: Caucasians are more commonly affected than other races such as Chinese, Japanese and African.

Some diseases like dry eye or dry mouth is associated with nodal marginal zone B-cell lymphoma.

Progression

Clinically and historically, non-Hodgkin's lymphoma can be subdivided into 2 groups: indolent (low grade) and aggressive (high grade) lymphomas. Nodal marginal zone B-cell lymphoma is under the indolent group - which means it has better prognosis but may not respond to treatment when compared to aggressive groups of lymphomas.

As for the course of the disease, it is dependent on the clinical stage when the disease is diagnosed.

The staging for non-Hodgkin's lymphoma (which is applicable for nodal marginal zone B-cell lymphoma as well) can be summarised as below:

Stage I - involvement of a single lymph node region or organ or site other than lymph nodes
Stage II - 2 or more lymph node regions involved on the same side of diaphragm
Stage III - 2 or more lymph node regions involved on both sides of diaphragm
Stage IV - one or more organs (eg bone marrow) involved

Each stage is subclassified into A and B (eg IIA), where B means presence of B symptoms (see below) while A means abscence of the following symptoms:

Unexplained fever > 38 Centigrade

Unexplained weight loss (defined as >10% of body weight in 6 months)

Night sweats

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