Burkitt lymphoma

Burkitt lymphoma, abbreviated BL, is an uncommon lymphoma with medium-sized cells.

General

• Extremely high proliferative rate & rate of apoptosis.
• Rare in adults -- 1-2% of adult lymphomas.
• Relatively common in children -- 30-50% of childhood lymphomas.

Pathophysiology

• Origin cell: germinal centre B cells (favoured) vs. memory B cells.

Subtypes

• Three subtypes recognized:

1. Endemic:
   • Found in Africa.
   • EBV (Epstein-Barr virus) associated.
2. Non-endemic:
   • Typical of the BL seen in the western world; EBV negative.
3. Immunodeficiency associated:
   • Associated with HIV infection.

Microscopic

Features:

• "Starry-sky pattern":
  • The stars in the pattern are: tingible-body macrophages.
    • Tingible-body macrophages = macrophages containing apoptotic tumour cells.
  • The tumour cells are the sky.
• Tumour cells:
  • Medium-sized (~1.5-2x the size of a RBC) with uniform size ("monotonous") -- key feature.
  • Round nucleus.
  • Small nucleoli.
  • Relatively abundant cytoplasm.
  • Brisk mitotic rate.

Images:

• Starry-sky pattern - Ed Uthman (WC).
• BL (nih.gov).

DDx:

• DLBCL.
• B cell lymphoma unclassifiable with features intermediate between DLBCL and Burkitt lymphoma.

IHC

Features:

• CD20 +ve.
• CD10 +ve.
• BCL6 +ve.
• EBER +ve.

Others:

• BCL2 -ve.

Cytologic definition

• t(8;14) (q24;q32) translocation.
• Several other variants -- involve MYC rearrangement.

Note:

• MYC rearrangement is typically assessed with an ISH break apart probe.

See also

• Lymphoma.
• Haematopathology.