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
Light chains	Wk	Either weak restricted κ or λ or undetectable expression
CD19	Wk/mod	Expression is expected, but less strong than normal B cells
CD20	Wk	Expression is expected, but characteristically weak
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
CD43	Mod	Similar to CD200, may be helpful in some cases

Pitfalls and atypical cases