title: Lymphoplasmacytic lymphoma and marginal zone lymphoma in the bone marrow: paratrabecular involvement as an important distinguishing feature.
abstract: OBJECTIVE
  The differential diagnosis between bone marrow involvement by lymphoplasmacytic lymphoma (LPL) and marginal zone lymphoma (MZL) is challenging because histology and immunophenotype of both diseases overlap. We revisited the diagnostic pathology features of both diseases in the bone marrow.
  
  
  METHODS
  We studied a series of bone marrow trephine biopsy specimens from 59 patients with Waldenström macroglobulinemia without extramedullary involvement and bone marrow biopsy specimens from 23 patients with well-characterized MZL who also had bone marrow involvement. H&E- and immunoperoxidase-stained sections of bone marrow trephine biopsy specimens as well as flow cytometry and classic cytogenetics performed on aspirations were reviewed. The study was complemented with MYD88 L265P mutation analysis of all samples.
  
  
  RESULTS
  The most distinguishing features of LPL with respect to MZL were focal paratrabecular involvement (P < .001), the presence of lymphoplasmacytoid cells (P < .001) and Dutcher bodies (P < .001), increased numbers of mast cells (P < .001), and the MYD88 L265P mutation (P < .001).
  
  
  CONCLUSIONS
  LPL can be reliably distinguished from MZL in the bone marrow by using a combination of pathology characteristics. Our findings stress the diagnostic importance of using the combination of the following parameters for a correct LPL diagnosis: paratrabecular infiltration, the presence of lymphoplasmacytoid cells and cells with Dutcher bodies, and an increased number of mast cells in addition to the presence of MYD88 mutation.
authors.affiliation: From the Department of Pathology, Akershus University Hospital, Oslo, Norway; University of Oslo, Oslo, Norway; assiavb@medisin.uio.no.
authors.forename: Assia
authors.initials: A
authors.lastname: Bassarova
authors.affiliation: University of Oslo, Oslo, Norway; Department of Pathology and.
authors.forename: Gunhild
authors.initials: G
authors.lastname: Trøen
authors.affiliation: Department of Pathology and.
authors.forename: Signe
authors.initials: S
authors.lastname: Spetalen
authors.affiliation: Section for Cancer Cytogenetics, Institute for Cancer Genetics and Informatics, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway; Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway; and.
authors.forename: Francesca
authors.initials: F
authors.lastname: Micci
authors.affiliation: Department of Pathology, University Health Network, Toronto, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Tierens
authors.affiliation: University of Oslo, Oslo, Norway; Department of Pathology, University Health Network, Toronto, Canada.
authors.forename: Jan
authors.initials: J
authors.lastname: Delabie
mesh_terms: D000328:Adult; D000368:Aged; D001853:Bone Marrow / Q000473:pathology*; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D018442:Lymphoma, B-Cell, Marginal Zone / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics; D016133:Polymerase Chain Reaction; D008258:Waldenstrom Macroglobulinemia / Q000175:diagnosis* / Q000235:genetics
chemical_list: C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88
keywords: Bone marrow; Hematopathology; Lymphoplasmacytic lymphoma; Marginal zone lymphoma; Paratrabecular