T cell lymphoblastic leukaemia/lymphoma associated with a microenvironment of thymic asteroid B cells in the bone marrow.
OBJECTIVE
Asteroid B cells are a component of normal thymus. It is currently unclear whether these cells are identifiable in T cell lymphoblastic leukaemia/lymphoma (T-ALL/LBL) of the thymus. The aim of this study was to identify asteroid B cells both in thymic and extrathymic tissue involved by T-ALL/LBL.


RESULTS
Thymic, lymph node (LN) and bone marrow trephine biopsy (BMTB) samples from eight patients with T-ALL/LBL were reviewed. All had been investigated by immunohistochemistry and one by fluorescent in situ hybridization (FISH). The BMTB samples of two of eight T-ALL/LBLs and LN sample in one of them showed the presence of asteroid-shaped B cells with dendritic cytoplasmic processes. These B cells also expressed CD23 and the features were akin to the unique thymic asteroid B cells. Both patients had aggressive/resistant disease. Cytogenetic analysis in one showed a complex translocation involving the T cell receptor beta (TCRB) gene at 7q35 and a distal region of 9q known to harbour the NOTCH1 gene.


CONCLUSIONS
This is the first report of T-ALL/LBL documenting the presence of an asteroid B cell-rich microenvironment at bone marrow and LN sites. In this small subset, T-ALL/LBL cells are possibly dependent upon asteroid B cells, and whether targeting of asteroid B cells with anti-CD20 monoclonal antibody in such cases will result in clinical benefit remains to be determined.
Naresh
Kikkeri N
KN
Departments of Histopathology and Haematology, Imperial College Healthcare NHS Trust, London, UK. k.naresh@imperial.ac.uk
May
Philippa C
PC
Reid
Alistair G
AG
Marks
Alexandra J
AJ
Macdonald
Donald
D
Kanfer
Ed
E
D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology*; D001853:Bone Marrow / Q000276:immunology / Q000473:pathology*; D001854:Bone Marrow Cells / Q000276:immunology / Q000473:pathology; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008198:Lymph Nodes / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000276:immunology / Q000473:pathology*; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology*