Follicular lymphoma is the most common of the indolent non-Hodgkin's lymphomas. 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 CD10,^[1] and usually negative for CD5.^[2]

It is also known as "nodular lymphoma".^[3]

Morphology

The tumor is composed of follicles containing a mixture of centrocytes (WHO nomenclature) or cleaved follicle center cells (older American nomenclature), "small cells", and centroblasts (WHO nomenclature) or large noncleaved follicle center cells (older American nomenclature), "large cells". These follicles are surrounded by non-malignant cells, mostly T-cells. In the follicles, centrocytes typically predominate; centroblasts are usually in minority.

Grading

According to the WHO criteria, the disease is morphologically graded into:^[4]

• grade 1 (<5 centroblasts per high-power field (hpf))
  • grade 2 (6-15 centroblasts/hpf)
  • grade 3 (>15 centroblasts/hpf).

Grade 3 is further subdivided into:

• • grade 3a (centrocytes still present)
  • the rare grade 3b (the follicles consist almost entirely of centroblasts)

The clinical relevance of this grading system is debated, although grades 1, 2 and 3a can be treated as an indolent disease, while grade 3b is an aggressive disease. Occasional cases may show plasmacytoid differentiation or foci of marginal zone or monocytoid B-cells.

Causes

A translocation between chromosome14 and 18 results in the overexpression of the bcl-2 gene. This overexpression causes a blockage of apoptosis, or programmed cell death. This translocation has been associated with the development of follicular lymphoma.

Treatment

There is no consensus regarding the best treatment algorithm, but watch-and-wait policies, (combinations of) alkylators and nucleoside analogues, anthracycline-containing regimens (eg. CHOP), rituximab, autologous and allogeneic hematopoietic stem cell transplantation have all been applied. The disease is regarded as incurable (although allogeneic stem cell transplanation may be curative, the mortality from the procedure is too high to be a first line option). The exception is localized disease, which can be cured by local irradiation. The typical pattern is one of good responses from treatment, followed by relapses some years later.

Prognosis

Median survival is around 10 years, but the range is wide, from less than one year, to more than 20 years. Some patients may never need treatment.

Epidemiology

Of all cancers involving the same class of blood cell, 22% of cases are follicular lymphomas.^[5]

References

1. ↑ Overview at UMDNJ
2. ↑
3. ↑
4. ↑
5. ↑

External links

• Strategies for Long-Term Survival
• Follicular Lymphoma Resource page - Patients Against Lymphoma
• Lymphoma information network

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