Blastic Natural Killer (NK)-Cell Lymphoma: Report of an Unusual CD4 Negative Case and Review of the CD4 Negative Neoplasms with Blastic Features in the Literature

Blastic Plasmacytoid Dendritic Cell Neoplasm: A Case Report and Clinicopathological Review

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is aggressive hematopoietic malignancy derived from the precursors of plasmacytoid dendritic cells. The present study reported a case of a 35-year-old BPDCN patient, who presented with scalp lesions without extracutaneous involvement of the lymph nodes (LNs), peripheral or bone marrow. Histopathological examination of scalp lesion revealed monomorphous diffuse infiltrate of small to medium-sized cells with irregular nuclear contours, pleomorphic nuclei, finely dispersed chromatin, inconspicuous nucleoli and scant amount of cytoplasm. Immunohistochemical staining showed diffuse positivity for CD45, CD4, CD 56, CD45 and negative for CD3, CD5, CD7, CD8, CD19, CD20, CD30, CD33, CD34, CD79a, CD99, CD117, TDT, and myeloperoxidase. Patient started treatment with acute lymphoblastic lymphoma protocol (Hyper-CVAD). Reevaluation after the second course showed marked regression of scalp lesion. The patient continued Hyper-CVAD protocol and planned for allogeneic stem cell transplant.

CD4-Negative Variant of Cutaneous Blastic Plasmacytoid Dendritic Cell Neoplasm With a Novel PBRM1 Mutation in an 11-Year-Old Girl

OBJECTIVES

We report a rare case of CD4- cutaneous blastic plasmacytoid dendritic cell neoplasm (BPDCN) with a novel PBRM1 mutation.

METHODS

An 11-year-old girl presented with an enlarged mass on her left arm and underwent an incisional biopsy.

RESULTS

Histopathologic examination and immunohistochemistry studies showed a monotonous proliferation of blasts that were CD4-, CD56+, and CD123+. There was no evidence of leukemic dissemination. Next-generation sequencing detected PBRM1 and CIC gene abnormalities. We confirmed and validated a novel PBRM1 mutation by conventional polymerase chain reaction and Sanger sequencing.

CONCLUSIONS

CD4- variant of BPDCN may be mistaken for myeloid sarcoma or extramedullary lymphoblastic leukemia/lymphoma because of their overlapping morphologic and immunophenotypic features; thus, a careful clinicopathologic evaluation is essential to reach the correct diagnosis. PBRM1 mutation seems to be a driver event in this case. Our study underscores the importance of alterations in chromatin remodeling in the pathogenesis of BPDCN.

Blastic Plasmacytoid Dendritic Cell Neoplasm: Analysis of Clinicopathological Feature and Treatment Outcome of Seven Cases

BACKGROUND

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), which is derived from the precursor of plasmacytoid dendritic cells, is a rare and highly aggressive hematologic malignancy. It has only recently been recognized as a distinct entity. BPDCN characteristically has a predilection for cutaneous involvement.

OBJECTIVE

The aim of this study was to describe the clinical and pathological features of BPDCN, and to review the treatment courses to analyze the prognosis and the optimal therapeutic approach.

METHODS

We retrospectively reviewed seven BPDCN cases registered in the Samsung Medical Center database between January 2010 and December 2014.

RESULTS

The median age of the patients was 52 years (range, 18~79 years), and six patients were male. The clinical staging was as follows: skin (n=5), lymph node (n=6), bone marrow (n=4), and peripheral blood (n=2). The skin manifestations were bruise-like tumefaction (n=4), erythematous nodule (n=4), or multiple erythematous papules (n=1). The pathological evaluation revealed dense diffuse or nodular infiltration of neoplastic cells, which were positive for CD4, CD56, and CD123 in the immunohistochemical analysis. Six patients received multiagent chemotherapy as the first-line treatment, alone (n=4), or followed by stem cell transplantation (SCT, n=1) or concurrent radiotherapy (n=1). The median progression-free survival after the first-line treatment was 6 months (range, 2~12 months).

CONCLUSION

Three different skin manifestations were observed, with pathological features analogous to each other. All patients who received chemotherapy without SCT achieved partial or complete response but experienced relapse. Furthermore, they showed various clinical courses irrelevant to the cutaneous involvement.

Optimized immunohistochemical panel to differentiate myeloid sarcoma from blastic plasmacytoid dendritic cell neoplasm

Myeloid sarcoma (MS) and blastic plasmacytoid dendritic cell neoplasm (BPDCN) can be difficult to distinguish morphologically, even with the use of extensive immunohistochemical studies. Three new research markers, myxovirus A (MxA), CLA/CD162, and CD303/BDCA-2, have been reported to be positive in BPDCN, but their clinical utility has never been tested. We compared these markers to other antibodies that have been used traditionally to distinguish MS from BPDCN to assess the utility of these newer antibodies in differential diagnosis. Formalin-fixed, paraffin-embedded tissue sections of 23 MS and 17 BPDCN cases were assessed using immunohistochemical analysis for CD4, CD14, CD33, CD43, CD56, CD68, CD123, CD163, myeloperoxidase, lysozyme, terminal deoxynucleotidyl transferase (TdT), T-cell leukemia 1 (TCL-1), MxA, cutaneous lymphocyte-associated antigen (CLA)/CD162, and blood dendritic cell antigen 2 (BDCA2)/CD303. We identified antibodies with a high predictive value of ≥ 90% and used these markers to develop an approach to classification using specific staining criteria. Diagnostic classification criteria were based on staining patterns of one or more of the seven markers. BPDCN was associated with positive staining for CD56, TdT, or TCL1, or negative staining for lysozyme. MS was associated with positive staining for lysozyme or myeloperoxidase, or negative staining for CD56, CD123, myxovirus, or TCL1. The immunohistochemical staining patterns observed using a panel that includes MPO, CD56, CD123, TCL1, TdT, and MxA, are predictive of MS or BPDCN. In this study, neither CD162 nor CD303 had good predictive value in distinguishing MS from BPDCN.

Immunophenotypic analysis of myeloperoxidase-negative leukemia cutis and blastic plasmacytoid dendritic cell neoplasm

Myeloid leukemia cutis (LC) and blastic plasmacytoid dendritic cell neoplasm (BPDCN) are morphologically indistinguishable malignancies that frequently manifest in the skin. Separating myeloperoxidase-negative LC from BPDCN may be particularly challenging. We identified a panel of immunohistochemical stains to distinguish myeloid LC (23 cases) from BPDCN (12 cases): myeloperoxidase, which stained 7 cases (30%) of LC and 0 cases (0%) of BPDCN; CD56, which stained 12 cases (52%) of LC and all 12 cases (100%) of BPDCN; CD4, which stained 2 cases (9%) of LC and all 12 cases (100%) of BPDCN; CD123, which stained 4 cases (17%) of LC and 10 cases (83%) of BPDCN; and Tcl-1, which stained 2 cases (9%) of LC and 9 (82%) of 11 cases of BPDCN. It is interesting that CD33 was not helpful; it stained 18 (78%) cases of LC and 11 cases (92%) of BPDCN. Our results indicate that a panel that includes CD4, CD56, CD123, and Tcl-1 can appropriately distinguish between these 2 entities.

Comments on cutaneous lymphomas: since the WHO-2008 classification to present

The last classification of lymphomas of the World Health Organization in 2008 made a few changes from the preceding classification. Although useful, at the same time, it has posed new questions, concerns, and dilemmas which have been raised in the literature. The current report highlights some of these controversies, of each of these primary cutaneous entities, going through cutaneous mature T-cell and NK-cell neoplasms, mature B-cell neoplasms, precursor neoplasms, and other entities, which for several reasons do not fit in the previous categories. It also reviews some advances on many of these lymphomas published in the last 2 years.

CD4-/CD56+/CD123+ Hematodermic Neoplasm Showing Early Liver Metastasis

Hematodermic neoplasm (HN) is a clinically aggressive neoplasm with a high incidence of cutaneous involvement and a risk of leukemic dissemination. In the recent WHO-EORTC classification, the term blastic natural killer cell lymphoma has been replaced with CD4+/CD56+ HN because of its derivation from a plasmacytoid dendritic cell precursor. Cases of HN that completely lack CD4 or CD56 expression, therefore represents a diagnostic problem. A 68-year-old Korean male was diagnosed with CD4-/CD56+ HN and treated with hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, dexamethasone) at initial treatment, and then switched to high dose methotrexate/cytarabine. His disease relapsed and resulted in death from bone and brain disease 6 months after complete clinical remission, despite diagnostic workups, including a radioisotope liver scan and ultrasound-guided fine needle aspiration biopsy. Further cytogenetic studies such as comparative genomic hybridization could elucidate the genetic mechanisms in the development and progression of lymphomas. We report an unusual case of 'CD4-/CD56+/CD123+ HN' showing early liver metastasis.

Uncommon cases of immature-type CD56+ natural killer (NK)-cell neoplasms, characterized by expression of myeloid antigen of blastic NK-cell lymphoma

Immature-type CD56(+) natural killer (NK)-cell neoplasms are classified as either myeloid/NK-cell precursor acute leukemia or blastic NK-cell lymphoma. We identified two cases of immature-type CD56(+) NK-cell neoplasms that were not categorizable as either of these entities. The first case involved a 74-year-old woman presenting with skin eruptions and pancytopenia due to bone marrow necrosis. Skin biopsy specimen revealed CD4(+), CD7(-), CD34(-), CD43(+), CD56(+), CD68(+), muramidase (lysozyme)(+), and myeloperoxidase (MPO)(-), and immunophenotyping of peripheral blood showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cytoplasmic (cy)CD68(+), CD123(+), and HLA-DR(+). The second case involved a 62-year-old man who had bilateral optic nerve tumor and presented with malignant cells in peripheral blood. Cell surface markers of malignant cells showed CD4(+), CD7(-), CD13(+), CD33(+), CD34(-), CD43(+), CD56(+), cyCD68(+), and HLA-DR(+). The phenotypes of tumor cells in both cases were compatible with blastic NK-cell lymphoma, except for the expression of myeloid antigen. Clinical presentations of these cases showed characteristics of both blastic NK-cell lymphoma and myeloid/NK-cell precursor acute leukemia.

CD4-negative variant of CD4+/CD56+ hematodermic neoplasm: description of three cases

BACKGROUND

CD4+/CD56+ hematodermic neoplasm (HN) (blastic natural killer (NK)-cell lymphoma) is a rare entity characterized by dense, monomorphous infiltrates of medium-sized cells with blastic appearance and a characteristic immunophenotype (positivity for CD4, CD56 and CD123). The combination of CD4 and CD56 positivity is thought to be so striking that it has been used to name this entity.

METHODS

Three cases of HN with ambiguous phenotypic profile were included in this study. In all cases, phenotypic, molecular and in situ hybridization studies were carried out.

RESULTS

All three cases showed an aberrant phenotype with negativity for CD4.

CONCLUSIONS

CD4-negative or CD56-negative cases of HN have been rarely reported in the literature and represent a diagnostic problem. Our three cases confirm that CD4 is not always expressed in these neoplasms. The term 'CD4+/CD56+ hematodermic neoplasm' adopted in the World Health Organization-European Organization for Research and Treatment of Cancer classification of cutaneous lymphomas may be misleading and should probably be revised in the light of all data published in the literature.