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:Typical HCL morphology, these medium sized cells have a distinctive "partly open" chromatin in an oval or bean-shaped nucleus, cytoplasm is blue/grey with typical hairy projections

Background to flow cytometric diagnosis

HCL expresses typical and unusual markers that together with morphology can allow diagnosed with some confidence using flow cytometry.

However, no marker is unique to HCL and unusual marker patterns can lead to diagnostic difficulty. If this is the case then the atypical features should be reported, since histopathology and molecular testing can each be used to further evaluate these cases.

Immunophenotype of CLL
Major markers useful in CLL diagnosis
Marker	Freq	Level	Comment
κ/λ		Stg	Expect strong restricted expression of κ or λ
FMC7		Stg	Typically this marker is strongly expressed
CD5		-	Infrequent but reported in some cases
CD10		-	Infrequently expressed in typica; CLL
CD11C		Stg	Strong expression of CD11c is typical of HCL
CD19		-	Expression is expected and may be strong in HCL
CD20		Stg	Expression is expected, and typically strong
CD23		-	Expression of CD23 is infrequent in HCL
CD25		wk	A typical and most frequently strongly expressed marker
CD38		wk	Not typically expressed by HCL, may be seen
CD43		-	Tends to be expressed at relatively high intensity
CD79b		wk	Expression is expected
CD103		-	A chracteristic marker of HCL with good specificity
CD138		-	Predominantly by cells with plasma cell differentiation
CD200		-	Characteristically positive in HCL and often strong

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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