Which lymphoma is strongly associated with overexpression of BCL2?

Explanation

## Correct Answer: A. Follicular lymphoma Follicular lymphoma is the classic lymphoma defined by **t(14;22) translocation**, which juxtaposes the BCL2 gene on chromosome 22 to the immunoglobulin heavy chain (IgH) promoter on chromosome 14. This translocation results in constitutive, unregulated overexpression of the BCL2 protein, a potent anti-apoptotic factor. BCL2 prevents programmed cell death by blocking mitochondrial outer membrane permeabilization, allowing malignant B cells to survive indefinitely despite accumulating additional genetic damage. Follicular lymphoma is the second most common lymphoma in India (after diffuse large B-cell lymphoma) and typically presents in advanced stage with nodal involvement. The BCL2 overexpression is so characteristic that it is used diagnostically—immunohistochemistry showing strong BCL2 positivity in germinal center cells (which normally have low BCL2) is a hallmark finding. This translocation is present in ~90% of follicular lymphomas and is considered the initiating event in lymphomagenesis, though additional mutations are required for progression to higher grades. ## Why the other options are wrong **B. Burkitt lymphoma** — Burkitt lymphoma is defined by **t(8;14) translocation** involving the MYC gene on chromosome 8, not BCL2. MYC overexpression drives proliferation and apoptosis, not anti-apoptosis. While Burkitt is highly aggressive and common in India (especially endemic in certain regions), its pathogenesis centers on MYC dysregulation, not BCL2. This is a classic NBE trap pairing two translocations. **C. Chronic lymphocytic leukemia** — CLL is characterized by **del(13q)** (most common, favorable prognosis), **del(11q)** (ATM loss), or **del(17p)** (TP53 loss), not BCL2 translocation. While CLL cells may have elevated BCL2 protein levels, this is not due to a specific translocation like in follicular lymphoma. CLL presents as a leukemia with circulating B cells, not primarily nodal lymphoma, and has different molecular drivers. **D. Diffuse large B-cell lymphoma** — DLBCL is the most common lymphoma in India but is genetically heterogeneous, involving multiple pathways (TP53, BCL6, MYC, PTEN mutations). While some DLBCL cases may have BCL2 translocation (especially those arising from follicular lymphoma transformation), BCL2 overexpression is not the defining feature. DLBCL is defined by morphology and clinical presentation, not a single translocation. ## High-Yield Facts - **t(14;22) translocation** in follicular lymphoma juxtaposes BCL2 to IgH promoter, causing constitutive anti-apoptotic protein overexpression. - **BCL2 prevents apoptosis** by blocking mitochondrial outer membrane permeabilization (MOMP) and cytochrome c release. - **~90% of follicular lymphomas** carry the BCL2 translocation; its presence is diagnostic and used in immunohistochemistry. - **Follicular lymphoma is indolent** (grade 1–2) but incurable; transformation to DLBCL occurs in ~10% of cases over 10 years. - **Burkitt lymphoma** (t(8;14)) and **CLL** (del(13q/11q/17p)) have different molecular drivers and are not BCL2-driven. - **BCL2 overexpression alone is insufficient** for malignancy; additional mutations (e.g., TP53, CREBBP) are required for progression. ## Mnemonics **BCL2 = Follicular (14;22)** **B**CL2 overexpression → **F**ollicular lymphoma via t(**14**;**22**). Remember: 14 = IgH chromosome, 22 = BCL2 chromosome. Use when seeing 'BCL2 translocation' in any question. **MYC = Burkitt (8;14)** **M**YC overexpression → **B**urkitt lymphoma via t(**8**;**14**). Opposite chromosome order from follicular. Use to distinguish Burkitt from follicular when both are options. ## NBE Trap NBE often pairs follicular lymphoma with Burkitt lymphoma to test whether students confuse the two translocations—both are lymphomas with characteristic chromosomal abnormalities, but t(14;22) drives anti-apoptosis (follicular) while t(8;14) drives proliferation (Burkitt). The trap is assuming "lymphoma + translocation = Burkitt." ## Clinical Pearl In Indian clinical practice, follicular lymphoma often presents in advanced stage (stage III–IV) with bulky nodal disease and is managed with observation ("watch and wait") in early stages, then rituximab-based chemotherapy at progression. The BCL2 translocation is so reliable that it guides prognosis and therapy—patients with BCL2+ follicular lymphoma may benefit from BCL2 inhibitors like venetoclax in relapsed disease. _Reference: Robbins Ch. 13 (Lymphoid Neoplasms); Harrison Ch. 104 (Lymphomas)_