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PRECURSOR LYMPHOID NEOPLASMS


B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA TEL/AML1

This FISH test mark the translocation t(12;21) between TEL gene on chomo 12 and AML1 in chromo 21. This ALL arises in B cell progenitor lineage (precursor B lymphoid neo). Normal genes show  red or green signals, and abnormal fusion gene show yellow signal. This leukaemia is more  common in children (not infants), show morphologically not specific blasts ( CD19+/10+, 34+,  negative: CD9/20 and some  CD13+, not necessarily indicating mixed myeloid phenotype). Px is good, not as good if kid > 10 or  high WBC count.   

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA BCR/ABL

May be detected by FISH  in a subset of Ph+ ALL arising in B cells more immature than other B-ALL cases. These  B Lymphoblastic Leukaemia/Lymphomas with t(9;22) are more common in adults than children. In kids  p190Kd BCR-ABL1 fusion detected. In  adults p210 (same fussion as CML) or p190.  Only rarely  lymphomatous involvement. No characteristic morphology of blasts . Positive for:  CD10+, 19+ and TdT+. Common  25+, 13+ and 33+. Negative for 117. Bad px both in adults and kids

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA MLL REARRANGED

May be detected by FISH. Harbour 11q23. Very young infants < 1 year. Involves CNS commonly. IHC: CD19+, 15+, NG2 (chondroitin sulfate) + . CD10 and 24 negative. Good prognosis.

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA WITH IL3-IGH

May be detected by FISH. Harbour t(5;14). Very rare in children or adults. Presents with increase circulating eos. CD19+, CD10+.  Px similar to other ALL

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA WITH E2A-PBX

May be detected by FISH. Harbour t(1;19). Very common in children. No unique morphology. Blasts are CD19+, CD10+ and CD9+ strong. CD34 is negative. Good px with therapy.

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA WITH HYPODIPLOIDY

Children or adults. <45 chromo, good px, no unique morphology. CD19+, 10+. FISH and karyotyping reveal hypodiploidy and commonly both techniques show discrepancy about # or chromosomes.  

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA WITH HYPERDIPLOIDY

> 50 chromo. Favorable leukaemia with no unique morphology, CD19+, 20+, 34+, 45-. More common in children than adults. If  simultaneous trisomies  4, 10 and 17 identified with regular cytogenetics or FISH, better px for the patient.

B LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA NOS

Common in children, good px. Convoluted PAS+ blasts showing small nucleoli.  Azurophilic granules and vacuoles may be present.  Typical case is pancytopenic kid with ALL involvemnt of nodes, testis, CNS, liver and spleen. If lymphoma is the presentation is common in bone, soft tissues and skin. Genetics show IGH rarrangement, sometimes T cell rearrangement but no specific genetic abnormalities. If t(17;19) or amplification of AML1 gene  detected by FISH (very rare abnormalities), the px is not good. Other genetic abnormalities are not specific. Markers by flow and IHC: 19+, 79a+ (b cell marker), cCD22+, 10+, Pax5+ (b cell marker), TdT+. CD45-. Myeloid markers 13 and 33 may be +. CD34 and 20 are variable. Carefull with Pax 5 that may be also present in some T ALL and some AML.

Normal B cell precursor (hematogone) vs abnormal B cell precursors ? Problem when evaluating bone marrow aspirates in kids after therapy. Hematogones may be indistinguishable from blasts in ALL and are expected when bone marrow is in the recovery after therapy.

Hematogones are intially CD34+, CD38++, CD10+, CD19+ with low CD20 and 22. Then CD34 is completly downregulated, CD10 partially downregulated and CD20 upregulated. Then CD10 is completely downregulated, CD38 partially downregulated and CD22 upregulated. When CD10 is totally downregulated we can consider the B cell a mature B cell.

Asynchronous expression of this antigens, for example simultaneous concurrent CD34 and CD20 or any aberrant over or underexpression is abnormal and never identified in hematogones.

T LYMPHOBLASTIC LEUKAEMIA/LYMPHOMA.

Common case is a young patient with mediastinal mass and nodes, although any lymphoid organ, liver, CNS and skin may be involved. In bx look for starry sky effect, sometimes present and similar to Burkitt's. Blasts  are morphologically similar to B cell blasts, with nucleoli a little bit more prominent. Most important marker lineage specific is cCD3.
The tumor may be divided in 4 stages of differentiation: proT, then PreT, then cortical and finally medullary.  All stages of T cell maturation are cCD3 and CD7 positive. All stages are CD2+ with exception of the first stage, proT. CD1a is only positive after cortical stage. CD34 is completly downregulates after cortical stage. ProT and PreT are CD4 and 8 negative. Cortical stage is CD4 and CD8 positive. Medullary is only either CD4 or CD8. Other markers commonly + indicating precursor T cell lymphoblasts are CD99 and TdT.  Rare cases CD79a, 13 or 33+ are described.  A very important test to confirm is  TCR. Some FISH pannels may be attempted with as much as 8 probes for different genetic abnormalities.  Px dependes of age (worst if older), WBC count (higher worst), stage and LDH. In general, this entity has worse px and more induction failure than B-ALL. However, T-ALL in adults is better than B-ALL.