Case 98 - Discussion

Uploaded: 2009-09-23, Updated: 2009-09-23

CLINICAL FEATURES

• Epidemiology:

  • Endemic: tropical Africa, most common childhood malignancy, peak 4-7 years of age, involves jaw or abdomen, 95% EBV positive.

  • Sporadic: mostly in children or young adults. 30% of childhood lymphomas

  • Immunodeficiency-associated: HIV.

• Locations:

  • Endemic: jaw and other facial bones in 50% cases, also distal ileum, cecum and omentum.

  • Sporadic: mostly in ileocecal area.

  • Immunodeficiency-associated: HIV.

• May present as B cell acute lymphoblastic leukemia FAB L3 (Burkitt’s leukemia). Call "Burkitt’s leukemia" if tumor cells present in blood and diffuse marrow involvement at diagnosis.

• Marrow involvement of 15-30%.

MICROSCOPIC FINDINGS

• Diffuse infiltration of monomorphic, medium-sized cells with starry sky pattern.

• Tumor cells:

  • Abundant basophilic cytoplasm. Some times "squared off" boarders.

  • Non-cleaved round nuclei with finely clumped and dispersed chromatin.

  • Multiple basophilic medium sized, paracentrally situated nucleoli.

• Imprints demonstrate deeply basophilic cytoplasm with lipid vacuoles.

IMMUNOPHENOTYPE

• Positive: CD10, CD79a, CD19, CD20, Ki-67 (almost 100%), BCL6, CD38

• EBV positive in endemic African cases and AIDS cases.

• Negative: BCL2, CD5, CD23, TdT.

CYTOGENETIC STUDIES

• C-myc translocations, very characteristic but not specific:

  • t(8;14)(q24;q32): c-myc and IgH, 75%.

  • t(2;8)(p12;q24): Ig Kappa and c-myc, 15%.

  • t(8;22)(q24;q11): c-myc and Ig Lambda, 10%.

TREATMENT AND PROGNOSIS

• Highly aggressive but potentially curable. Curable with aggressive therapy in 60% cases.

REFERENCES: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, Fourth Edition. 2008.