Flow cytometry: Follicular Lymphoma

Background

Typical MCL expresses CD5, but can be distinguished from CLL by the absence of CD23 and CD200.

However, individual markers may not be expressed in all cases - this can cause diagnostic difficulty particularly with atypical forms of MZL or occasionally other B-cell lymphoproliferative disorders. Generally it is correct to advise cytogenetic or genetic testing to confirm.

Immunophenotype of FL
Major markers useful in CLL diagnosis
Marker	Freq	Level	Comment
κ/λ			Expect κ or λ expression, undetectable in rare cases
FMC7		-	Occasionally seen, FMC7 is not typical of FL
CD5		-	Expression of CD5 is characteristic of MCL
CD10		Strg	Expression is expected though not universal in FL
CD11C			Expression is not typically seen in FL
CD19		-	Expression is expected, but may be weak or undectable
CD20		-	Expression is expected, rare cases may have CD20 loss
CD23		-	Typically not expressed by MCL, may rarely be expressed
CD25			Not typical of MCL, not generally strong as HCL
CD38		-	Expression is expected in MCL but CD138 should be absent
CD43		-	Lower expression than in CLL, may be helpful in some cases
CD79a			Expression is expected and should be stronger than CLL
CD103		-	Not expressed by MCL, consider HCL if found
CD138		-	Predominantly expressed at plasma cell differentiation
CD200		-	Characteristically (though not always) negative in MCL

Key to table:

Markers most useful in initial diagnosis are underlined in blue text

Key to colour code for expression frequency Click for link

Key to expression strength code and use Click for link

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