Tryptase-positive mast cells accompany lymphocytic as well as lymphoplasmacytic lymphoma infiltrates in bone marrow trephine biopsies.
OBJECTIVE
To investigate the specificity of increased bone marrow mast cell numbers in lymphoplasmacytic lymphoma (LPL) and to evaluate the relationship between mast cell number and the immunoglobulin phenotype of neoplastic lymphoid cells.


RESULTS
Retrospective study of bone marrow trephine biopsy specimens from patients with LPL, compared with selected cases representing chronic lymphocytic leukaemia (CLL) and multiple myeloma (MM) of known immunoglobulin light and heavy chain phenotype. Bone marrow mast cells were counted following immunohistochemical staining of sections for mast cell tryptase. We have confirmed previous observations that mast cell numbers are increased in bone marrow infiltrates of LPL. However, we found similarly high mast cell numbers in CLL. High mast cell numbers were associated with neoplastic lymphoid cells expressing an IgM kappa phenotype. Mast cell numbers were low in all cases of MM studied and in controls with no lymphoma present. We observed an apparent bias towards kappa light chain expression in our cases of LPL.


CONCLUSIONS
Mast cell number should not be considered a reliable factor in the differential diagnosis of LPL and CLL when assessing bone marrow histology. Possible bias towards kappa light chain expression in LPL requires further study, as do the mechanism and functions of mast cell recruitment by neoplastic lymphoid cells.
Wilkins
B S
BS
Division of Cancer Sciences, University of Southampton, Southampton SO16 6YD, UK. bsw2@soton.ac.uk
Buchan
S L
SL
Webster
J
J
Jones
D B
DB
D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001853:Bone Marrow / Q000473:pathology*; D002452:Cell Count; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D007150:Immunohistochemistry; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008407:Mast Cells / Q000201:enzymology / Q000473:pathology*; D008875:Middle Aged; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology; D012697:Serine Endopeptidases / Q000032:analysis*; D053802:Tryptases
D007136:Immunoglobulins; D012697:Serine Endopeptidases; D053802:Tryptases