Case 415

Submitting Author: Bakshi, Nasir Ahmed, MD
Institution: KFSH & RC
Additional authors:Tarek M Owidah, MD, FRCPA; Claudia U Walter, PhD
Session: B Lymphoblastic Leukemia/Lymphoma

HISTORY

An 8-year-old male presented with with two weeks history of fever, lower limb bone pain and pallor. At admission, he had liver of 4-5 cm and spleen 3 cm. No significant lymphadenopathy.

WBC 10.01 x 10^9/L, HGB 95 g/L, HCT 0.280, MCV 81.6 fL, Platelet count 14 x 10^9/L. Peripheral blood smear examination shows 35% circulating blast cells.

DETAILS

BONE MARROW ASPIRATE: non-particulated with cellular trails and with diffuse infiltration by blasts representing more than 90% of all nucleated cells. The blasts were mainly medium-sized with a relatively low N/C ratio with cytoplasmic and nuclear vacuolation and bluish cytoplasm. Other hematopoietic cell lines were markedly suppressed.

BONE MARROW TREPHINE BIOPSY: comprised of segment measuring 1 x 0.2 cm partially clotted and fragmented. Good intertrabecular bone marrow spaces were seen showing hypercellular marrow with cellularity of almost 100% depicting diffuse infiltration by blasts. Other hematopoietic cells lines were markedly suppressed.

IMMUNOHISTOCHEMISTRY AND FLOW CYTOMETRY

Flow performed on the bone marrow aspirate demonstrated an abnormal population of blasts expressing CD45 (moderate), CD19, HLA-DR, CD22, CD15 and NG2 along with surface Lambda, and IgM. These blasts were negative for CD20, CD10, CD34 and TdT.

CYTOGENETIC FINDINGS

48,XY,+X,t(4;11)(q21;q23),i(8)(q10),+i(8)(q10)[11]/46,XY[4]

Interpretation and Conclusion:

The abnormal clone had a t(4;11) translocation as primary abnormality together with other numerical and structural changes. A case of MLL positive childhood acute leukemia due to t(4;11).

MOLECULAR FINDINGS

FISH tested for MLL rearrangement at 11q23 was positive in 81% nuclei.

FISH tested for C-MYC rearrangement was negative.

Other molecular markers for B/T-ALL were negative.

INTERESTING FEATURES

This case shows that B-ALL with MLL rearrangement with t(4;11) translocation can express a ‘mature’ B-cell phenotype with seemingly Burkitt-like morphology and immunophenotype and may as well represent a distinct subset.

PROPOSED DIAGNOSIS

B-cell Lymphoblastic Leukemia with Burkitt-like immunomorphologic features and MLL gene rearrangement.

CONSENSUS DIAGNOSIS

Mature B-cell leukemia/lymphoma with t(4;11)