Bone marrow - nonneoplastic
Benign changes
Plasmacytosis

Author: Xiangrong (Alex) Zhao, M.D., Ph.D. (see Authors page)

Revised: 11 July 2017, last major update January 2014

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PubMed Search: Plasmacytosis [title] bone marrow

Cite this page: Plasmacytosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonemarrowplasmacytosis.html. Accessed December 13th, 2017.
Definition / general
Epidemiology
Clinical features
  • Can be associated with fever, leukocytosis, skin rash
  • May also see lymphadenopathy, dyspnea, hepatosplenomegaly, jaundice
  • Case specific presentation varies by etiology
Diagnosis
  • Bone marrow biopsy for histomorphologic evaluation and immunophenotypic analysis of plasma cells to demonstrate polyclonality
  • When possible, bone marrow aspirate for cytomorphologic evaluation, differential count, flow cytometric analysis (to demonstrate plasma cell polyclonality and confirm lack of aberrant immunophenotype) and cytogenetic / molecular analyses to rule out neoplastic process, if clinically indicated
  • CBC and peripheral blood smear to evaluate peripheral blood involvment
  • If peripheral blood is involved, use serum protein electrophoresis to assess polyclonality
Case reports
  • 31 year old man with systemic inflammatory syndrome and hepatic inflammatory cell infiltration caused by IL6 producing pheochromocytoma (Endocr J 2005;52:193)
  • 41 year old man with polyclonal reactive peripheral blood plasmacytosis mimicking plasma cell leukemia (Leuk Lymphoma 2003;44:379)
  • 53 year old woman with methimazole induced aplastic anemia caused by hypocellular bone marrow with plasmacytosis (Thyroid 2004;14:231)
  • 72 year old woman with reactive plasmacytosis mimicking multiple myeloma and primary Sj√∂gren syndrome (J Korean Med Sci 2005;20:506)
  • 77 year old man with polyclonal plasma cell proliferation with marked hypergammaglobulinemia and multiple autoantibodies (Ann Clin Lab Sci 2006;36:479)
  • 89 year old woman with polyclonal proliferation of plasma cells associated with marked hypergammaglobulinemia (Int J Hematol 2005;81:62)
  • Systemic polyclonal B immunoblastic proliferation with marked peripheral blood and bone marrow plasmacytosis (Am J Clin Pathol 1992;98:222)
Treatment
  • Mainly symptomatic and supportive
  • Treat the underlying condition
Microscopic (histologic) description
  • Bone marrow biopsies often show hypercellularity with an increase in plasma cells / plasmacytoid cells, in perivascular or interstitial distribution
  • Background trilineage hematopoiesis is present
  • Myeloid and erythroid precursors show normal morphology and may be variably decreased in number, depending on the extent of replacement by plasma cells
  • Megakaryocytes are often normal in number, morphology and localization
Microscopic (histologic) images

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Lymph node biopsy

Differentiation of mature plasma cells

Cytology description
  • Spectrum of plasma cell differentiation
  • Plasmablasts appear large with scant basophilic cytoplasm, prominent nuclei, dispersed fine chromatin, conspicuous nucleoli
  • Immature plasma cells show abundant basophilic cytoplasm, round nuclei with condensed chromatin
  • With differentiation, plasma cells show more basophilic cytoplasm with perinuclear halos and eccentric nuclei
Peripheral smear description
  • Prominent increase of plasma cells / plasmacytoid cells in a variety of sizes and maturation stages
Peripheral smear images

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Stages of plasma cell differentiation

Positive stains
  • Express markers in normal plasma cells:
    • On tissue sections: CD45, CD19, CD79a, CD138, CD38, MUM1, kappa and lambda light chains (immunohistochemical and in situ hybridization)
    • In flow cytometric analysis: CD45, CD19, CD79b, CD138, CD38, cytoplasmic kappa and lambda light chains, CD27, CD81
Negative stains
Flow cytometry description
  • Flow cytometric analysis of plasma cells in bone marrow aspirate demonstrates polytypic plasma cells with no immunophenotypic aberration:
    • Forward scatter and side scatter larger than those of lymphocytes
    • Dimmer CD45, moderate CD19, negative CD20, bright CD38, bright CD138
    • Variable intensity of HLA-DR
    • Polytypic cytoplasmic kappa and lambda light chains
    • Negative for surface kappa and lambda light chains
    • Negative for CD56
    • A small portion of larger, brighter HLA-DR+ cells can be detected, representing plasmablasts or early plasma cells which are negative for cytoplasmic light chains while the smaller, dim HLA-DR+ cells represent mature plasma cells
Flow cytometry Images

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Plasma cells in bone marrow

Molecular / cytogenetics description
  • Molecular analysis demonstrates polyclonality of the plasma cells
  • Cytogenetic analysis (e.g. karyotyping, FISH) confirms the lack of cytogenetic aberrations
Differential diagnosis