Positive for tetraploidy, consistent with a favorable prognostic implication in B-ALL / LBL.FISH: Interphase FISH analysis performed on formalin fixed paraffin embedded tissue shows the following results.Proliferative fraction is > 95% based on Ki67. Not expressed are CD117, CD3, CD30, myeloperoxidase, lysozyme, EBV (EBER) and MYC. Immunohistochemistry demonstrates that the neoplastic cells are of precursor B cell origin (CD45+, PAX5+, CD79a+, TdT+, CD10+, CD43+, CD34 subset +, CD20 few scattered cells +). Mitoses and apoptotic bodies are readily observed. Microscopic description: Biopsy of the tongue shows benign squamous mucosa with an extensive and diffuse subepithelial infiltrate of medium sized to large neoplastic cells, some containing a prominent nucleolus.B lymphoblastic lymphoma, not otherwise specified (see microscopic description and FISH).Reference: Swerdlow: WHO Classification of Tumors of Haematopoietic and Lymphoid Tissues (Medicine), 4th Edition, 2017.NOTCH1 gene mutations can lead to shorter survival in adult T-ALL / LBL.Del (9p) with loss of tumor suppressor gene CDKN2A occurs in at least 30%.TCR loci at 14q11.2, 7p35 and 7p14-15, with various partner genes.In T-ALL / LBL, recurrent cytogenetic abnormalities can also be seen:.Most T-ALL / LBL harbor T cell receptor gene rearrangement simultaneous IGH gene rearrangement present in about 20%.t(5 14) Iе…ѓ-IGH: uncertain prognostic significance reactive eosinophilia is characteristic.BCR-ABL1-like IGH-CRLF2 translocation (and less commonly EPOR): CRLF2 translocation frequent in Down syndrome standard risk in children and high risk in adolescents and adults more frequent in Hispanics and Native Americans.t(v 11q23) MLL gene rearrangement: poor prognosis.t(9 22) BCR-ABL1 (Philadelphia chromosome): very poor prognosis incidence increases with age, 3% of childhood cases and 25% of adult.Hyperdiploidy: favorable prognosis trisomies 4, 10 and 17 have the best prognosis.

t(12 21) TEL-AML: very favorable prognosis most common rearrangement in childhood B-ALL / LBL (25%), with cures of > 90%.Recurrent genetic abnormalities in B-ALL often have prognostic significance:.Most B-ALL show clonal IgH (immunoglobulin heavy locus) gene rearrangement simultaneous T cell receptor (TCR) gene rearrangement present in up to 70%.е…ѓ subtype: now corresponds to leukemic phase of Burkitt lymphoma, a high grade mature B cell lymphoma ( Blood Cancer J 2017 7:e577).L2 subtype: more heterogeneous appearance, with slightly more cytoplasm and more prominent nucleoli, resembling myeloblasts.L1 subtype: most common, with intermediate size, uniform features, scant basophilic cytoplasm, slightly condensed chromatin with inconspicuous / absent nucleoli.L1 and L2 subtype segregation not shown to correlate with clinical or biologic behavior thus, most commonly used for descriptive purpose at this time.Revised criteria to the original French American British (FAB) classification of ALL cytologic subtypes.Lymphoblasts may be oval in shape and display an indented nucleus with finely dispersed chromatin and inconspicuous nucleoli.

Partial nodal involvement of T-LBL may have a predominantly interfollicular distribution.

In nodal involvement, blasts usually display a diffuse growth pattern.

B and T cell precursors are morphologically indistinguishable.

Proliferation of typically small to medium sized primitive cells but some tumor cells may appear as larger blasts containing cytoplasmic vacuoles.

In tissue masses or marrow, effacement of architecture by round blue cells raises the differential diagnoses of ALL / LBL versus neuroblastoma, Ewing sarcoma and other mimickers.

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