## Distinguishing Burkitt Lymphoma from DLBCL ### Cytogenetic Hallmark **Key Point:** The t(8;14)(q24;q32) translocation involving MYC and the immunoglobulin heavy chain (IGH) locus is the defining cytogenetic abnormality of Burkitt lymphoma and is virtually pathognomonic. ### Comparative Features | Feature | Burkitt Lymphoma | DLBCL | |---------|------------------|-------| | **Cytogenetics** | t(8;14) MYC/IGH (95%) | Complex karyotype; MYC rearrangement rare (<10%) | | **Cell size** | Medium, uniform cells | Large, heterogeneous cells | | **Proliferation** | Ki-67 ~100% | Ki-67 30–90% | | **Morphology** | Starry-sky pattern | Diffuse infiltration | | **CD10 expression** | Positive (GCB type) | Variable | | **Age** | Typically <40 years, often children | Older adults (median 60–70 years) | ### Why t(8;14) is the Gold Standard Discriminator **High-Yield:** While both lymphomas are aggressive B-cell neoplasms with high proliferation rates and may show CD20+ phenotype, the **t(8;14) translocation is unique to Burkitt lymphoma**. This cytogenetic abnormality: 1. Juxtaposes the MYC oncogene to the IGH enhancer, causing constitutive MYC overexpression. 2. Is detected by karyotyping, FISH, or next-generation sequencing. 3. Is required for WHO diagnosis of Burkitt lymphoma. 4. Is absent in DLBCL (which may have other translocations like t(14;18) or complex patterns). **Clinical Pearl:** Burkitt lymphoma is the most aggressive human malignancy but has excellent cure rates (>90%) with intensive chemotherapy (e.g., Hyper-CVAD) if diagnosed early. DLBCL has more heterogeneous outcomes depending on IPI score and molecular subtype. ### Why Other Features Are Not Discriminators **Warning:** Both lymphomas express CD20, have high Ki-67, may involve extranodal sites, and can show starry-sky morphology — these are NOT specific to Burkitt. The starry-sky appearance (tingible body macrophages engulfing apoptotic debris) is seen in both but is more characteristic of Burkitt; however, it is not pathognomonic and can occur in other high-grade lymphomas.
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