Bone marrow nonneoplastic
Benign changes
Plasmacytosis
Last author update: 1 January 2014
Last staff update: 19 April 2023
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PubMed Search: Plasmacytosis [title] bone marrow
Table of Contents
Definition / general | Epidemiology | Clinical features | Diagnosis | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Peripheral smear description | Peripheral smear images | Positive stains | Negative stains | Flow cytometry description | Flow cytometry images | Molecular / cytogenetics description | Differential diagnosisCite this page: Zhao X. Plasmacytosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bonemarrowplasmacytosis.html. Accessed April 19th, 2024.
Definition / general
- Plasmacytosis in bone marrow and peripheral blood can be monoclonal (plasma cell neoplasm) or polyclonal
- See also lymphoid aggregates, polymorphous reactive lymphoid hyperplasia and systemic polyclonal B immunoblastic proliferation
Epidemiology
- Reactive plamacytosis in bone marrow can be seen in both neoplastic and nonneoplastic conditions:
- Seen as reactive component in myeloproliferative neoplasms, myelodysplastic syndromes, mastocytosis (Sem Hop 1983;59:2119) or other malignancies
- Seen in polyclonal hypergammaglobulinemia (Int J Hematol 2005;81:62), systemic polyclonal B immunoblastic proliferation (Am J Clin Pathol 1992;98:222, J Forensic Sci 2001;46:156), autoimmune disorders (e.g. SLE), immunocompromise (e.g. HIV infection) and infections (Leuk Lymphoma 2003;44:379)
- Particularly common (86%) in HIV+ patients (Indian J Pathol Microbiol 2005;48:7, Clin Immunol 2001;100:250)
- When strict diagnostic criteria are applied, benign polyclonal plasmacytosis in bone marrow and peripheral blood is uncommon
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 Sjögren 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
Images hosted on other servers:
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
Negative stains
- CD56 (Am J Pathol 2002;160:1293, Histopathology 2004;44:375) is negative in benign plasma cells (as benign polyclonal plasmacytosis) and ~80% of plasma cell leukemia (Leukemia 1998;12:1977)
- Lack of CD56 expression should not be used solely to rule out plasma cell neoplasm
- Negative for CD20 and surface light chains (as in normal plasma cells)
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
- Castleman disease: see Ann Pathol 1996;16:133
- Myeloma / plasmacytoma: CD56+, clonal, immature and pleomorphic plasma cells
- Plasma cell neoplasms, in particular plasma cell leukemia when peripheral blood is involved
- Plasmacytic SLL / CLL
