Flow cytometric marker pattern of chronic lymphocytic leukaemia

Background

Typical CLL can be diagnosed with some confidence using flow cytometry.

However, individual markers may not be expressed in all cases - this can cause diagnostic difficulty particularly in distinguishing CLL from atypical cases of MCL or MZL. If this is the case then the atypical features should be reported, and the possibility of alternative diagnoses acknowledged.

Note also that cases with a low lymphocytosis (<1x10⁹) may represent monoclonal B-lymphocytosis with CLL phenotype (click here for more).

Immunophenotype of CLL
Major markers useful in CLL diagnosis
Marker	Freq	Level	Comment
κ/λ			Expect weak restricted κ or λ or absent expression
FMC7			May be expressed by atypical cases, generally absent
CD5		-	Characteristic of CLL, usually less strong than on T cells
CD10		-	Infrequent in CLL, consider FL if detected
CD11C		wk	Expressed in some cases, but tends to be weak
CD19		-	Expression is expected, but less strong than normal B cells
CD20		wk	Expression is expected, but characteristically weak
CD23		-	Characteristic of CLL, although can rarely be weak or absent
CD25		wk	Expressed by many cases of CLL but characteristically weak
CD38		wk	Expressed by some cases of CLL, typically weak
CD43		-	Similar to CD200, may be helpful in some cases
CD79a		wk	Expression is expected, but characteristically weak
CD103		-	Not expressed by CLL, consider HCL if found
CD138		-	Predominantly expressed at plasma cell differentiation
CD200		-	Characteristically positive in CLL and negative in MCL

Key to table:

Markers most useful in initial diagnosis are underlined in blue text

Key to colour code for expression frequency Click for link

Key to expression strength code and use Click for link

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