Step 1 topics → Hematology and Oncology → Burkitt and Mantle Cell Lymphomas

Burkitt and Mantle Cell Lymphomas

USMLE Step 1 trap: Confuses Burkitt's t(8;14)/MYC with follicular lymphoma's t(14;18)/BCL-2. Burkitt lymphoma is caused by t(8;14) (or variants t(2;8) and t(8;22)), placing MYC under Ig promoter control, driving uncontrolled proliferation; t(14;18) is follicular lymphoma.

Burkitt and mantle cell lymphomas are two high-yield B-cell malignancies that USMLE Step 1 tests primarily through their defining chromosomal translocations, immunophenotypes, and histologic findings. The most common wrong answer: confusing t(8;14) with t(14;18) because both involve chromosome 14's IgH locus. Burkitt's t(8;14) brings MYC next to IgH, driving relentless proliferation; follicular lymphoma's t(14;18) brings BCL-2, blocking apoptosis — completely different mechanism, completely different disease. Burkitt is defined by t(8;14) and MYC overexpression; mantle cell by t(11;14) and cyclin D1 overexpression. Both come with characteristic histologic and clinical features tested in vignette form, including the starry sky pattern and tumor lysis syndrome risk.

The trickiest part of this topic is the translocation overlap trap. Students frequently mix up t(8;14) with t(14;18) — the shared chromosome 14 is enough to cause confusion under pressure. Burkitt's t(8;14) moves MYC next to the heavy chain Ig locus, driving uncontrolled cell proliferation. Follicular lymphoma's t(14;18) moves BCL-2 next to the same locus, blocking apoptosis — totally different mechanism, totally different disease. Similarly, mantle cell and CLL share CD5 positivity, which is unusual for B-cell lymphomas, but CD23 cleanly separates them: CLL is CD23-positive, mantle cell is CD23-negative with cyclin D1.

USMLE Step 1 also tests the clinical implications of these diagnoses. Burkitt has the highest proliferation index (Ki-67 near 100%) of any lymphoma and carries serious tumor lysis syndrome risk — that's a management pearl the exam will test in a clinical scenario. The 'starry sky' histology is a classic image question, but students commonly misread it as reflecting low turnover when it actually reflects the opposite. Know the three Burkitt subtypes (endemic, sporadic, immunodeficiency-associated) and their EBV associations, and understand why mantle cell — despite not being the most aggressive lymphoma — is notoriously difficult to cure.

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Common misconceptions

Common mistake
Wrong: Burkitt lymphoma is caused by the t(14;18) BCL-2 translocation.
Right: Burkitt lymphoma is caused by t(8;14) (or variants t(2;8) and t(8;22)), placing MYC under Ig promoter control, driving uncontrolled proliferation; t(14;18) is follicular lymphoma.
The shared chromosome 14 between t(8;14) and t(14;18) is a classic trap on USMLE Step 1. In Burkitt lymphoma, chromosome 8 donates MYC, which gets placed under the control of the immunoglobulin heavy chain promoter on chromosome 14 — this drives relentless cell proliferation. In follicular lymphoma, chromosome 18 donates BCL-2, which is placed under the same Ig promoter — this blocks apoptosis instead. The mechanism and the disease are completely different; always pair the non-14 chromosome (8 vs. 18) with the specific oncogene (MYC vs. BCL-2) to lock in the correct association.
Common mistake
Wrong: The 'starry sky' histologic pattern in Burkitt lymphoma reflects low cell turnover.
Right: The 'starry sky' pattern reflects extremely HIGH cell turnover — the 'stars' are macrophages engulfing apoptotic tumor cells amid a dark background of densely packed lymphoma cells.
The 'starry sky' pattern is counterintuitive because the bright spots (the 'stars') might look peaceful, but they mark sites of intense cellular destruction. The stars are macrophages that have engulfed apoptotic tumor cells — and there are so many of them because Burkitt lymphoma has the highest proliferation rate of any lymphoma (Ki-67 ~100%), meaning cells are also dying at an extraordinary rate. The dark background is densely packed viable lymphoma cells. High turnover, not low — this pattern should immediately trigger thoughts of aggressive disease and tumor lysis syndrome risk.
Common mistake
Wrong: Mantle cell lymphoma expresses CD23 like CLL/SLL.
Right: Mantle cell lymphoma is CD5+/CD23-NEGATIVE with cyclin D1 overexpression from t(11;14), whereas CLL is CD5+/CD23-POSITIVE without cyclin D1.
Both mantle cell lymphoma and CLL are mature B-cell neoplasms that are CD5-positive, which is already unusual — CD5 is normally a T-cell marker. The key distinguishing feature is CD23: CLL is CD23-positive, and mantle cell is CD23-negative. Beyond surface markers, mantle cell has t(11;14) causing cyclin D1 overexpression, which CLL lacks entirely. On the exam, if you see CD5+/CD23−/cyclin D1+ in a middle-aged man, that's mantle cell; CD5+/CD23+ without cyclin D1 is CLL.
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What the exam tests

  1. Identify the correct chromosomal translocation for Burkitt lymphoma (t(8;14)) and its molecular consequence (MYC overexpression driving proliferation), and distinguish it from the t(14;18) translocation of follicular lymphoma.
  2. Interpret the 'starry sky' histologic pattern in Burkitt lymphoma — recognize that it reflects extremely high cell turnover, with macrophages engulfing apoptotic tumor cells, not low proliferation.
  3. Know the three subtypes of Burkitt lymphoma (endemic, sporadic, immunodeficiency-associated) and their differential association with EBV infection.
  4. Recognize tumor lysis syndrome as a major complication of Burkitt lymphoma treatment given its near-100% Ki-67 proliferation index.
  5. Identify mantle cell lymphoma by its t(11;14) translocation, cyclin D1 overexpression, and immunophenotype (CD5+/CD23−), and distinguish it from CLL/SLL (CD5+/CD23+) in a clinical or pathology vignette.

Can you avoid these mistakes?

A biopsy from a jaw mass in a child in sub-Saharan Africa shows sheets of intermediate-sized lymphocytes with scattered pale macrophages on H&E. Cytogenetics reveals a translocation involving chromosome 8 and the immunoglobulin heavy chain locus. What is the translocation, what oncogene is dysregulated, and what immediate treatment complication must you anticipate?
A pathology slide shows a 'starry sky' pattern. A classmate says this represents a low-grade lymphoma with slow cell turnover. How do you correct them, and what does the pattern actually reflect mechanistically?
Flow cytometry on a lymph node biopsy from a 60-year-old man shows CD5+, CD19+, CD23−, and cyclin D1 overexpression. What is the diagnosis, what translocation is responsible, and how does the immunophenotype differ from the most common B-cell leukemia that also expresses CD5?
A patient with a newly diagnosed high-grade B-cell lymphoma is about to start chemotherapy. Before initiating treatment, labs show rising potassium, phosphate, and uric acid with a falling calcium. Which lymphoma subtype is most classically associated with this complication, and why does its biology make this risk so high?

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