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Lymphoma - Non B cell neoplasms

T/NK cell disorders

Blastic plasmacytoid dendritic cell neoplasm


Reviewer: Dragos Luca, M.D. (see Reviewers page)
Revised: 5 July 2012, last major update August 2011
Copyright: (c) 2001-2011, PathologyOutlines.com, Inc.

Definition
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● Clinically aggressive tumor derived from the precursors of plasmacytoid dendritic cells (also known as professional type 1 interferon producing cells or plasmacytoid monocytes), with a high frequency of cutaneous and bone marrow involvement and leukemic dissemination (WHO 2008)

Terminology
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● Synonyms: blastic NK-cell lymphoma, agranular CD4+ NK-cell leukemia, blastic NK leukemia/lymphoma, agranular CD4+ CD56+ hematodermic neoplasm

Epidemiology
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● Very rare (< 100 cases reported)
● Usually ages 45+ years, but can affect all ages; mean age at diagnosis 61-67 years, also children
● 75% male

Etiology
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● Tumor cells may derive from plasmacytoid monocytes present in healthy volunteers, as both are CD4+ CD56+ CD43+ CD68+ HLA-DR+, negative for other markers (Am J Surg Pathol 2002;26:852)
● Not associated with Epstein-Barr virus
● May be associated with myelodysplasia

Clinical features
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● Skin (virtually 100%), bone marrow / peripheral blood (60-90%), lymph node (40-50%)
● Solitary/multiple nodules/plaques; usually disseminated at presentation
● Various cytopenias, especially thrombocytopenia

Case reports
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● Infant with multiple masses (Arch Pathol Lab Med 2001;125:413)
● 31 year old woman with diabetes and 15 cm leg lesion (Pathol Lab Med 2003;127:e267)
● 64 year old man with coexisting B-cell lymphoproliferative disorder (Am J Dermatopathol 2011;33:e31)
● Two patients with primary cutaneous disease (Pathol Res Pract 2011;207:55)
● 3 men and one woman (J Korean Med Sci 2005;20:319)

Treatment and prognosis
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● Aggressive, with poor response to chemotherapy; some respond initially but recur (Am J Clin Pathol 2002;117:41)
● Median survival 12-14 months with 80-90% demonstrating initial response to chemotherapy
● Relapse is the rule (skin, soft tissue, CNS); terminal fulminant leukemic phase in most cases
● Rare long-lasting remissions associated with young age, acute leukemia chemotherapy and allogeneic stem cell transplantation
● 10-20% associated with or progress to AML or AMML, with or without underlying myelodysplasia (Cancer 2002;94:2401)

Postulated normal counterpart
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● Precursor of plasmacytoid dendritic cells (α-interferon producing cells)

Clinical images
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Infiltrated plaque on the leg

Gross description (skin)
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● Usually multiple bruise-like deep red plaques/tumors

Micro description
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● Diffuse monotonous infiltrate of blasts (medium size with scant agranular cytoplasm, fine chromatin resembling AML blasts, irregular nuclei, small nucleoli) with NK-cell lineage differentiation
● Skin cases usually involve entire dermis (including adenexa) and may extend to subcutis but donít involve epidermis; Grenz zone present
● Occasionally have single file pattern of infiltration; usually no coagulative necrosis, no angiocentric infiltrate, no angioinvasion
● Lymph nodes: diffuse interfollicular and medullary involvement
● Bone marrow: variable involvement from subtle to massive, with variable dysplasia

Micro images
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Skin biopsies


Fig 1: diffuse monotonous dermal infiltrate of medium sized cells; 2-cells resemble blasts with minimal cytoplasm and fine immature chromatin; 3-CD56+; 4-TdT+

   
Various images


CD56+, CD43+, negative for CD45 and TdT

Cytology description
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● Membrane-bound cytoplasmic microvacuoles (pearl necklace-like), pseudopod formation

Flow cytometry images
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Fig A-flow cytometry shows CD56+ and CD34 cells (upper left), no surface CD3 (upper right), cytoplasmic CD3 and no MPO (lower left), no CD13 or CD7 (lower right); B-karyotype shows unbalanced abnormalities of #11p, 15q and 18q

Positive stains
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● CD56, CD43, CD45RA, CD68 (50%); also HLA-DR, CD4, CD123, CD7, TdT (1/3 of cases), BDCA2/CD303, TCL1, CLA, MxA, CD33
● Lack of CD56 (rarely) does not rule out if CD4, CD123 and TCL1 are positive
● Rare: CD2, CD36, CD38
● Cytotoxic molecules (granzyme B, TIA1, perforin) are positive by flow cytometry but usually negative by immunohistochemistry

Negative stains
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● CD3, CD5, CD13, CD16, CD19, CD20, CD34, CD79a, CD117, LAT, EBV, myeloperoxidase, non-specific esterase, lysozyme

Genetics and Molecular
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● No T or B cell receptor genes rearrangement; complex karyotypes, nothing specific
● Six major recurrent abnormalities: 5q21 or 5q34 (72%), 12p13 (64%), 13q13-21 (64%), 6q23-qter (50%), 15q (43%), -9 (28%, Blood 2002;99:4154)

Differential diagnosis
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● Extranodal NK/T-cell lymphoma, nasal type: cells not blastic
● B/T lymphoblastic lymphoma: TdT+, CD56-, T-cell receptor is rearranged
● Granulocytic sarcoma: may be CD56+, TIA-, usually evidence of myeloid disorders
● Chronic myelomonocytic leukemia with massive nodal/extranodal localization of plasmacytoid dendritic cells: morphologically mature, CD56-, TdT-

Additional references
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Am J Clin Pathol 2007;127:687, Arch Pathol Lab Med 2007;131:149, Am J Clin Pathol 2005;123:662, Hematologica 2010;95:1873

End of Lymphoma - Non B cell neoplasms > T/NK cell disorders > Blastic plasmacytoid dendritic cell neoplasm


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