Test

Background

Typical CLL can be diagnosed with some confidence using flow cytometry. CLL cells express low levels of B-cell receptor associated molecules (e.g. CD19, CD79B and sIg) together with CD5 and CD23 in typical cases. However, atypical cases are regularly encoutered and can cause diagnosic difficulty.

Immunophenotype of CLL
Major markers useful in CLL diagnosis
κ/λ		wk	Either weak restricted κ or λ or undetectable expression
CD5		Mod	Characteristic of CLL, usually less strong than on T cells
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
CD43		Wk/ Mod	Similar to CD200, may be helpful in some cases
CD79A		Wk	Expression is expected, but characteristically weak
FMC7	Wk	May be expressed by atypical cases, generally absent
CD200	Mod	Characteristically positive in CLL and negative in MCL
CD5	Mod	Characteristic of CLL, usually less strong than on T cells
CD23	Mod	Characteristic of CLL, although can rarely be weak or absent
CD43	Mod	Similar to CD200, may be helpful in some cases
Other markers with diagnostic relevance
CD11c	Wk	Expressed in some cases, but tends to be wk
CD103	-	Not expressed by CLL, consider HCL if found
CD10	Wk	Rare in CLL, consider FL if detected

Pitfalls and atypical cases