Burkitt Lymphoma

#155

What is Burkitt lymphoma (BL)?

A highly aggressive, high-grade B-cell non-Hodgkin lymphoma with extremely rapid growth.

What is unique about the growth rate of BL?

It has the shortest doubling time of all human cancers (~25 hours).

What cell type does BL arise from?

Mature B cells.

What is required to diagnose BL?

Tissue biopsy with histology, immunophenotyping, and cytogenetics.

What is the classic histologic appearance of BL?

“Starry-sky” pattern with macrophages among malignant cells.

What creates the “starry-sky” appearance?

Tingible-body macrophages containing debris scattered among tumor cells.

What are tingible-body macrophages?

Macrophages that phagocytose apoptotic tumor debris.

What are the cytologic features of BL cells?

Medium-sized cells, high nuclear-to-cytoplasmic ratio, basophilic cytoplasm with vacuoles.

What is the immunophenotype of BL?

Positive for CD19, CD20, CD22, CD10, and surface IgM.

Is TdT positive or negative in BL?

Negative (helps distinguish from ALL).

What is the key oncogene in BL?

MYC gene.

Where is the MYC gene located?

Chromosome 8.

What is the most common translocation in BL?

t(8;14) involving MYC and immunoglobulin heavy chain.

What are other MYC translocations in BL?

t(2;8) and t(8;22) involving light chain loci.

What is the effect of MYC overexpression?

Increased production of proteins, lipids, and nucleotides for rapid cell growth.

What virus is strongly associated with BL?

Epstein-Barr virus (EBV).

What is another name for EBV?

Human herpesvirus 4 (HHV-4).

How does EBV contribute to BL?

Promotes B-cell proliferation increasing risk of MYC translocation.

What geographic association exists for BL?

Endemic BL occurs in equatorial Africa.

What infection is associated with endemic BL?

Plasmodium falciparum malaria.

How does malaria contribute to BL?

Primes B cells, increasing susceptibility to EBV-driven transformation.

What are the three variants of BL?

Endemic, sporadic, and immunodeficiency-associated.

What is the typical age group for BL?

Primarily children, but also young adults.

Which BL variant is most common worldwide?

Sporadic BL.

What is the typical presentation of endemic BL?

Rapidly growing jaw or facial bone tumor.

What is the typical presentation of sporadic BL?

Abdominal mass, often in ileocecal region.

What symptoms are seen in sporadic BL?

Abdominal distension, ascites, may mimic appendicitis.

What organs are commonly involved in sporadic BL?

Ileocecum, mesentery, kidneys, ovaries.

What is characteristic of immunodeficiency-associated BL?

Lymph node and bone marrow involvement in HIV patients.

What CD4 count is typical in HIV-associated BL?

Usually >200 cells/mL.

What percentage of immunodeficiency BL is disseminated?

70 percent present with late-stage disease.

What complication is common in BL due to high turnover?

Tumor lysis syndrome.

What causes tumor lysis syndrome?

Rapid destruction of tumor cells releasing potassium, phosphate, and uric acid.

How is tumor lysis syndrome prevented?

IV fluids and rasburicase before and during chemotherapy.

What labs may be elevated in BL?

Lactate dehydrogenase and uric acid.

What imaging is used in BL workup?

CT scans of chest, abdomen, and pelvis.

What additional tests are needed for staging?

Bone marrow biopsy and CSF analysis.

How quickly should treatment begin for BL?

Within 48 hours of diagnosis.

What is the mainstay of BL treatment?

High-dose combination chemotherapy.

What additional therapy is commonly added?

Rituximab (anti-CD20 monoclonal antibody).

What is used for CNS prophylaxis in BL?

Intrathecal methotrexate or cytarabine.

Why is CNS prophylaxis important in BL?

High risk of CNS involvement.

What is the prognosis of BL with treatment?

Good, with >60 percent 5-year survival in children and young adults.

Why is early treatment critical in BL?

Rapid growth can quickly become life-threatening without prompt therapy.

What is Burkitt leukemia?

A form of BL with extensive bone marrow involvement.

What was Burkitt leukemia previously called?

Acute lymphoblastic leukemia L3 type.

What is the hallmark clinical takeaway of BL?

Extremely fast-growing tumor that is highly aggressive but highly treatable with early therapy.