Test
From haematologyetc.co.uk
Background
Typical CLL can be diagnosed with some confidence using flow cytometry. However, atypical cases are regularly encoutered and can cause diagnosic difficulty.
This image shows a typical CLL cells and a dot plot of CD45/SSc. Note that although the CLL cells (shown in blue) generally lie close to the position of normal lymphocytes, consistent with their "anergic nature": CLL cells express low levels of B-cell receptor associated molecules (e.g. CD19, CD79B and sIg) and also will generally have lower expression of CD45 than typical T cells (shown in red) or NK cells (shown in green). CLL often has a wide range of CD45 expression causing the population to have a "sausage like" shape on a CD45/SSc plot.
file CLL image file CD45CLL.jpg left 250px
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 |
Other markers with diagnostic relevance |
Immunophenotype:
Markers of B-lineage
- Immunoglobulin light chains: expect either light chain restriction with low intensity, or undetectable expression
- CD19 should be detected, but intensity is generally weak in CLL
- CD20 has expected expression in CLL, but intensity is generally weak
- CD79b expression is characteristically weak in CLL
Markers allowing diagnostic distinction
- FMC7 will have low or absent expression, high expression is particularly may suggest alternative disorders such as MCL or MZL
- CD5 should be expressed at moderate intensity in CLL (note also on expressed on mcl and occasionally on other lpd)
- CD23 has expected expression in CLL often at low intensity, generally absent in mcl but variably present on other lpd
- CD200 expressed on most CLL cases as well as other b-lpd but is most frequently absent in mcl optional markers extended panel for atypical cases
- CD43 a pan b-cell marker with expected expression in CLL; frequently but not always absent in mcl
Pitfalls