Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Abnormal

Increased Mature appearing B-cells


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› Microscopic Features:

• Slightly (1.5x) larger than a mature RBC
• High nuclear to cytoplasmic ratio but with
• Round mature Nucleus (clumped chromatin)
• Nucleoli are absent
• Cytoplasm is scant, light blue and lacks granules

› Normal % blood-PB, marrow-BM, lymphoid tissue-LN:

• PB: None (abnormal lymphocytes are rarely present)
• BM: None (abnormal lymphocytes are rarely present)
• LN: None (abnormal lymphocytes are rarely present)

› May Resemble:

• Mature T-cells (can't distinguish T-cell and B-cell based on morphology)
• Reactive lymphocyte [Compare]
• Monocyte [Compare]

› Differential Diagnoses:

If increased in blood, lymph node or bone marrow: Infection Neoplastic (mature B-cell lymphoma or leukemia such as but not limited to CLL or Follicular Lymphoma)

› Classic Immunophenotype:

• CD19+
• CD20+
• CD22+
• TdT-
• CD34-

› Cartoon Image:


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› Misc:

• Morphologically you cannot distinguish mature T-cells from mature B-cells Note: Neoplastic mature B-cells are clonal processes which can be shown through their light chain restriction (kappa restricted or lambda restricted) along with their characteristic immunophenotype (e.g. CD5 expression by CLL and CD10 expression by follicular lymphoma)