BPDCN: Difference between revisions

Latest revision as of 13:59, 2 January 2024

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Blastic plasmacytoid dendritic cell neoplasm (BPDCN)

This is a rare diagnosis but one that presents some practical diagnostic difficulties since BPDCN is derived from myeloid cells and therefore may have morphological and immunophenotypic characteristics which overlap with typical AML or acute undifferentiated leukaemia. Morphologically the primitive cells may resemble AML or have lymphoid morphology, and a skin rash is present in most cases. In view of the diagnostic overlap, correlation with morphology, histopathology and clinical information is important when making this diagnosis.

Using standard diagnostic panels, cases of BPDCN generally have the following features:

BPCDN typically have features of primitive phenotype: the cells typically lie in the "blast area" - with dim to moderate CD45 expression with low side scatter. CD7, TdT, CD38 and HLA-DR are frequently expressed. CD34 is characteristically absent
Lineage-defining markers of myeloid, T or B cell are not expressed: i.e. there is no expression of MPO, CD14 or lysozyme; cCD3 is not expressed, and CD19 is not expressed (as well as CD20, cCD22, CD79a)
One or more myeloid lineage-associated features may be detected: expression of CD33 is relatively common (>50%), CD117 may also be expressed (<20%), CD13 may be found although is infrequent (<5%). Therefore cases may fit the criteria to assign myeloid lineage (two myeloid-associated markers).

Diagnosis is then based on specific criteria:

For cases meeting the criteria above, then the following are required:
Cells of BPDCN will express: bright CD56 and/or CD4
Then will also meet either Criteria set 1 OR Criteria set 2
Criteria for BPCN (set 1)	CD123 expressed together with one of: CD303, CD304, TCF4, TCL1
Criteria for BPCN (set 2)	CD123 not expressed but at least three of CD303, CD304, TCF4, TCL1 are expressed

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-'''Blastic plasmacytoid dendritic cell neoplasm (BPDCN)'''
+<div style="width: 200px">
+{| class="wikitable" style="border-left:solid 5px green;border-right:solid 5px green;border-top:solid 5px black;border-bottom:solid 5px black; font-size:90%; color:navy"
+| colspan="1"''|[[The flow cytometric diagnosis of AML|Return to previous page]]''
+|}
+</div>
 ----
-''Morphologically the primitive cells may resemble monocytic AML and typically lie in the "blast area" with dim to moderate CD45 expression with low side scatter which can raise the possibility of an AML diagnosis. A skin rash is present in most cases.''
+<div style="width: 95%">
+{| class="wikitable" style="border-style: solid; border-width: 5px; color:black"
-----
+|colspan="1" style = "font-size:90%; color:black; background:#ddeee1"|'''Blastic plasmacytoid dendritic cell neoplasm (BPDCN)'''
-'''Potential difficulties in diagnosis:'''
+|}
-The most common source of confusion is with the diagnosis of monoblastic AML:
-*The cells have a primitive phenotype with CD7 and TdT frequently expressed but CD34 should be absent.
-*BPDCN cells will not express MPO or CD3.
-*CD79A and CD20 should not be expressed
-*The expression of CD33 is relatively common with CD117 also expressed in some cases, this allows potetial assignment to the AML category.
-----
+This is a rare diagnosis but one that presents some practical diagnostic difficulties since BPDCN is derived from myeloid cells and therefore may have morphological and immunophenotypic characteristics which overlap with typical AML or acute undifferentiated leukaemia. Morphologically the primitive cells may resemble AML or have lymphoid morphology, and a skin rash is present in most cases. In view of the diagnostic overlap, correlation with morphology, histopathology and clinical information is important when making this diagnosis.</br></br>
-'''What to look for:'''
+Using standard diagnostic panels, cases of BPDCN generally have the following features:
+*BPCDN typically have features of primitive phenotype: the cells typically lie in the "blast area" - with dim to moderate CD45 expression with low side scatter. CD7, TdT, CD38 and HLA-DR are frequently expressed. '''CD34 is characteristically absent'''
+*'''Lineage-defining markers of myeloid, T or B cell are not expressed''': i.e. there is no expression of MPO, CD14 or lysozyme; cCD3 is not expressed, and CD19 is not expressed (as well as CD20, cCD22, CD79a)
+*'''One or more myeloid lineage-associated features may be detected''': expression of CD33 is relatively common (>50%), CD117 may also be expressed (<20%), CD13 may be found although is infrequent (<5%). Therefore cases may fit the criteria to assign myeloid lineage (two myeloid-associated markers).
+</br>Diagnosis is then based on specific criteria:
-Bright expression of: CD56 is generally accompanied by CD36, CD38, CD43, CD71, and HLA-DR,
+<div style="width: 95%"; >
-To confirm the diagnosis look also for plasmacytoid dendritic cell (PDC) associated markers: CD123, CD303, CD304, TCF4, TCL1 .
+{| class="wikitable"
+!colspan="2" style = "background:palegrey;border:solid"|For cases meeting the criteria above, then the following are required:</br>
+|-
+!colspan="2" style = "background:white; font-size:90%; border:solid; "|Cells of BPDCN will express: '''bright CD56 and/or CD4'''
+|-
+!colspan="2" style = "background:palegrey;border:solid"|Then will also meet either Criteria set 1 '''OR''' Criteria set 2</br>
+|-
+!colspan="1" style = "background:white;border:solid; font-size:90%;"|Criteria for BPCN (set 1)
+!colspan="1" style = "background:white;border:solid; font-size:90%;"|'''CD123 expressed''' together with one of: CD303, CD304, TCF4, TCL1
+|-
+!colspan="1" style = "background:white;border:solid; font-size:90%;"|Criteria for BPCN (set 2)
+!colspan="1" style = "background:white;border:solid; font-size:90%;"|'''CD123 not expressed''' but at least three of CD303, CD304, TCF4, TCL1 are expressed
+|}
 ----
-WHO diagnostic criteria allow BPDCN to be diagnosed:
-*in the presence of CD123 and one other PDC-associated marker in addition to CD4 and/or CD56,
-*in the presence of three PDC-associated markers and the absence of CD34 and other cell type-specific markers including CD3, CD14, CD19, lysozyme, and MPO.
-Given the presence of other hematologic malignancies with similar phenotypes, correlation with histomorphology, clinical information and IHC studies is always necessary to make a definitive diagnosis of BPDCN.

BPDCN: Difference between revisions

From haematologyetc.co.uk

Latest revision as of 13:59, 2 January 2024