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<span style="color: navy>'''Pitfalls and atypical cases'''</span>
 
 
<span style="color: navy>'''Immunophenotype:'''</span>
 
 
'''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
 
 
<span style="color: navy>'''Pitfalls'''</span>

Revision as of 13:21, 15 June 2023


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
Other markers with diagnostic relevance
CD43 Mod Similar to CD200, may be helpful in some cases


Pitfalls and atypical cases

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