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Cancer Genet. 2019 Nov 9;240:40-44. doi: 10.1016/j.cancergen.2019.11.002. [Epub ahead of print]

Molecular and phenotypic characterization of an early T-cell precursor acute lymphoblastic lymphoma harboring PICALM-MLLT10 fusion with aberrant expression of B-cell antigens.

Author information

1
Department of Hematology/Oncology, Mayo Clinic, Mangurian Building, 4500 San Pablo Road, Jacksonville, FL 32224, United States. Electronic address: khurana.sharad@mayo.edu.
2
Department of Internal Medicine, Mayo Clinic, Jacksonville, FL, United States.
3
Division of Laboratory Genetics and Genomics, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, United States.
4
Center for Individualized Medicine-Biomarker Discovery, Mayo Clinic, Rochester, MN, United States.
5
Department of Hematology/Oncology, Mayo Clinic, Mangurian Building, 4500 San Pablo Road, Jacksonville, FL 32224, United States.
6
Department of Laboratory Medicine and Pathology, Mayo Clinic, Jacksonville, FL, United States.

Abstract

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is usually diagnosed based on the presence of immature lymphoid marker terminal deoxynucleotidyl transferase (TdT), and T-cell specific markers, specifically CD3, by immunohistochemistry (IHC) staining on bone marrow and/or extramedullary tissue. We present a novel, TdT and CD3 negative, aggressive early T-cell precursor LBL (ETP-LBL) initially misdiagnosed as a high grade B-cell lymphoma due to expression of CD79a and the erroneous detection of BCL2/IGH fusion. The patient was eventually evaluated using molecular diagnostic techniques, including fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) assays that demonstrated PICALM-MLLT10 fusion and a NOTCH1 mutation in the absence of BCL2/IGH fusion. The use of NGS, specifically mate-pair sequencing (MPseq), subsequently confirmed an in-frame PICALM-MLLT10 fusion. Our retrospective analysis showed that PICALM-MLLT10 fusion has no association with CD3/TdT negativity, as 6/49 T-ALL/LBL cases from Mayo Clinic database (01/1998-09/2018), including this case, were noted to have PICALM-MLLT10 fusion; however, none of the other cases were associated with CD3/TdT negativity. We emphasize the importance of a comprehensive hematopathologic evaluation including multiple molecular studies for the appropriate interrogation and classification of a difficult acute leukemia diagnosis, and to prevent potential diagnostic errors of clinical significance.

KEYWORDS:

Early T-cell precursor LBL (ETP-LBL); Fluorescence in situ hybridization (FISH); Immunohistochemistry (IHC); Mate-pair sequencing (MPseq); Next generation sequencing (NGS); PICALM-MLLT10

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