Bone marrow - nonneoplastic
Benign changes
Systemic polyclonal B immunoblastic proliferation

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

Revised: 12 July 2017, last major update March 2014

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PubMed Search: Systemic polyclonal B immunoblastic proliferation

Cite this page: Systemic polyclonal B immunoblastic proliferation. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonemarrowsystemicpolyclonal.html. Accessed December 17th, 2017.
Definition / general
Laboratory
  • CBC: usually leukocytosis with absolute lymphocytosis; neutrophilia with left shift may be present
  • Anemia and thrombocytopenia are almost always present
  • Positive antiglobulin test, as the anemia is frequently immune mediated
  • Hypergammaglobulinemia, polyclonal per immunofixation electrophoresis (IFE)
Prognosis
  • Rapid regression of disease process may occur
  • Most patients who recover do not relapse but patients may die in acute phase (Cancer 1988;61:1350)
Case reports
Treatment
  • Supportive care and treatment tailored to associated immune disorder
  • Variable response to treatment; many respond to steroids while others require chemotherapy (vincristine and cyclophosphamide) (Cancer 1988;61:1350)
Microscopic (histologic) description
  • Hypercellular marrow with extensive infiltration resembling lymphoma or plasmablastic myeloma, due to lymphocytes, immunoblasts, plasma cells, intermediate forms
  • Focal lymphocytic aggregates are characteristically present, varying from inconspicuous to large
  • Similar infiltrate may be seen in lymph nodes with complete effacement of nodal architecture
  • Immunohistochemistry is critical to demonstrate polytypic nature of process
Cytology description
  • Bone marrow aspirate smear shows numerous lymphocytes, immunoblasts, plasma cells
  • Prominent immunoblastic cytomorphology with intensely basophilic cytoplasm, relatively coarse chromatin pattern, distinct central nucleoli
  • Frequently, evidence of maturation to plasma cells can be seen
Peripheral smear description
  • Elevated WBC count with absolute lymphocytosis including reactive lymphocytes, immunoblasts, plasma cells
  • Neutrophilia with left shift may be present
  • Anemia and thrombocytopenia are almost always present
Positive stains
  • B cell markers and plasma cell markers in appropriate cellular components
  • Plasma cells and immunoblasts are polytypic for immunoglobulin light chain staining pattern
Negative stains
  • No aberrant antigen expression
  • No light chain restriction
Flow cytometry description
  • Polytypic B cells per surface (B cells) or cytoplasmic (plasma cells) light chain expression
  • No aberrant antigen loss or expression
Molecular / cytogenetics description
  • PCR reveals germline immunoglobulin and T cell receptor genes in polyclonal rearrangement pattern
  • Rarely, oligoclonal B and T cell populations are demonstrated by PCR
  • Clonal cytogenetic abnormalities have been identified in a subset of patients, raising the possibility of a cryptic neoplastic proliferation
Differential diagnosis
  • Non-Hodgkin lymphoma with immunoblastic morphologies and some plasma cell dyscrasias (plasmablastic myeloma) have monotypic light chain expression