## **Core Concept**
Follicular lymphoma is a type of non-Hodgkin lymphoma characterized by the presence of a specific chromosomal translocation. This translocation involves the immunoglobulin heavy chain gene and a proto-oncogene, leading to overexpression of the latter.

## **Why the Correct Answer is Right**
The correct answer, **t(14;18)**, involves the translocation between chromosome 14 and chromosome 18. This translocation places the **BCL2** gene, which is located on chromosome 18, under the control of the immunoglobulin heavy chain enhancer on chromosome 14. As a result, BCL2 is overexpressed, leading to an inhibition of normal programmed cell death (apoptosis) and contributing to lymphomagenesis. The BCL2 protein is a key regulator of apoptosis, and its overexpression is a hallmark of follicular lymphoma.

## **Why Each Wrong Option is Incorrect**
* **Option A: t(8;14)** - This translocation is commonly associated with Burkitt lymphoma, where it leads to the overexpression of the **MYC** oncogene. While it is a significant translocation in lymphomas, it is not characteristic of follicular lymphoma.
* **Option B: t(11;14)** - This translocation involves the **CCND1** gene (cyclin D1) and is commonly seen in mantle cell lymphoma. It leads to the overexpression of cyclin D1, driving cell cycle progression.
* **Option D: t(2;5)** - This translocation results in the creation of the **ALK** gene (anaplastic lymphoma kinase) fusion protein and is associated with anaplastic large cell lymphoma. It is not related to follicular lymphoma.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the **t(14;18)** translocation, leading to **BCL2** overexpression, is not only diagnostic but also a prognostic marker for follicular lymphoma. Detection of this translocation can aid in the diagnosis and potentially guide treatment decisions.

## **Correct Answer: B. t(14;18)**