Test

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 may represent monoclonal B-lymphocytosis with CLL phenotype (see here for definitiion).

Immunophenotype of CLL
Major markers useful in CLL diagnosis
Marker	Freq	Level	Comment
κ/λ		wk/ abs	Expect weak or absent restricted κ or λ expression
FMC7		Wk	May be expressed by atypical cases, generally absent
CD5		Mod	Characteristic of CLL, usually less strong than on T cells
CD10		-	Rare in CLL, consider FL if detected
CD11C		Wk	Expressed in some cases, but tends to be weak
CD19		Wk/ mod	Expression is expected, but less strong than normal B cells
CD20		Wk	Expression is expected, but characteristically weak
CD23		Wk/ Mod	Characteristic of CLL, although can rarely be weak or absent
CD25		Wk/ Mod	Expressed by many cases of CLL but characteristically weak
CD38		Wk	Expressed by some cases of CLL, typically weak
CD43		Wk/ Mod	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		Mod	Characteristically positive in CLL and negative in MCL

Key to table:

Click for key to expression frequency Key

Click for key to expression strength Key

Markers most useful in initial diagnosis are |'underlined in blue text

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