HematologyOutlines - Atlas
Blood/Blood Cells and Cellular Components ›› Lymphocytes ›› Abnormal

Chronic Lymphocytic Leukemia (CLL)*

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Microscopic Features:
  • Increased number of Small to intermediate sized lymphocytes in the peripheral blood (usually >5000 absolute count)
  • Minimal nuclear membrane irregularities
  • Nucleoli are absent
  • Background smudge cells (smeared partially broken up cells) are common but not specific to CLL
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: None
  • LN: None
May Resemble:
  • Lymphocyte (mature)
  • Reactive lymphocyte
  • Mantle cell leukemia (Mantle Cell Lymphoma in blood)
Differential Diagnoses:

Reactive lymphocytosis
Mantle cell leukemia
Other mature B or T-cell leukemias

Classic Immunophenotype:
  • CD19+
  • CD20dim+
  • CD5+
  • CD23+
  • BCL1-
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  • CLL is a low grade B-cell leukemia mostly seen in elderly In tissue it is called Small Lymphocytic Lymphoma (SLL)