Natural Killer Cell Precursor Acute Lymphoma/Leukemia Presenting in an Infant

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1 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Presenting in an Infant Yasodha Natkunam, MD, PhD; Athena M. Cherry, PhD; P. Joanne Cornbleet, MD, PhD Lymphoma/leukemia derived from immature natural killer (NK) cells occur most commonly in adults and are characterized by blastic cytologic features and an aggressive outcome. Predilection for extranodal sites and absence of the Epstein-Barr virus associated with mature NK cell malignancies further distinguish this entity. We present a NK precursor acute lymphoma presenting with multiple masses in an infant without circulating blasts or marrow replacement by disease. The diagnostic difficulty arose from several factors, including young age, presentation with multiple masses, blastic cytologic features mistaken for a small, round, blue cell tumor, and the absence of lineagespecific markers. The CD56, CD4, CD, MPO,cytoplasmic CD, CD45, CD7, HLA-DR, and TdT immunophenotype of this neoplasm overlaps with previously reported cases of myeloid/nk precursor acute leukemia and blastic NK cell lymphoma/leukemia. This case emphasizes the need for a strong index of suspicion to recognize this rare entity and to distinguish it from solid tumors and other hematolymphoid neoplasms that occur in infancy. (Arch Pathol Lab Med. 00;5:4 48) Neoplasms of natural killer (NK) cell precursors comprise a rare subset of NK and NK-like T-cell malignancies and include myeloid/nk precursor acute leukemia and blastic (or blastoid) NK cell lymphoma/leukemia. 5 These entities are characterized by blastic morphologic features, an immunophenotype compatible with immature NK cell derivation (CD56 CD57, CD6 ) and the absence of the Epstein-Barr virus (EBV) highly associated with mature NK cell neoplasms. 7 Propensity for extranodal sites, such as the skin, soft tissue, and mediastinum, with dissemination to lymph nodes and bone marrow delineates the aggressive clinical behavior of NK cell precursor neoplasms. Because of the blastlike appearance of the constituent cells, their differential diagnosis includes lymphoblastic lymphoma/acute lymphoblastic leukemia (LBL/ALL) and acute myeloid leukemia (AML). The diagnostic separation of precursor NK lymphoma/leukemia from LBL/ALL and AML is important because precursor NK lymphoma/leukemia may show poor or partial response to standard chemotherapeutic regimens used in Accepted for publication July 8, 000. From the Department of Pathology, Stanford University Medical Center, Stanford, Calif. Reprints: Yasodha Natkunam, MD, PhD, Department of Pathology, Stanford University Medical Center, 00 Pasteur Dr, Stanford, CA 9405 ( ynatkunam@yahoo.com). the treatment of non-hodgkin lymphomas and acute leukemias., In addition, the predilection of NK cell precursor neoplasms for extranodal involvement increases their likelihood of misdiagnosis as nonhematolymphoid malignancies, including small, round, blue cell tumors. 8 We describe the clinical, histologic, immunophenotypic, and cytogenetic findings of an unusual case of NK precursor acute lymphoma/leukemia that occurred in an -monthold child with a clinical presentation and immunophenotype distinct from previously reported cases. REPORT OF A CASE An -month-old white girl presented with intermittent fevers and cervical adenopathy of 6 weeks duration. A prodrome of progressive adenopathy was present since 6 months of age. Her status was normal after spontaneous vaginal delivery at full term following an uncomplicated pregnancy. On computed tomography (CT) scans, mediastinal adenopathy impinging on the superior vena cava and trachea and posterior auricular, cervical, mesenteric, and ileofemoral adenopathy were detected. Thoracic and abdominal visceral involvement and hepatosplenomegaly were absent. There was no other pertinent history or family history. Serologic testing for EBV and cytomegalovirus were negative. Biopsy specimens of a 9.0-cm cervical lymph node and the bone marrow revealed an undifferentiated malignant neoplasm. No circulating blasts were present on the peripheral blood smear despite marrow involvement. Initial immunophenotypic studies were done on paraffin sections of the lymph node because material was not available for flow cytometry. The atypical cells lacked reactivity for epithelial, mesenchymal, neuroendocrine, T- cell, B-cell, myeloid, and histiocytic differentiation. Weak staining for CD4 and CD99 and strong staining for CD4 were detected. These studies and the morphologic features were most consistent with a blastic lymphoma/leukemia, although definitive characterization of the neoplasm was not made at this time. An aggressive chemotherapy regimen combining induction therapy for acute leukemia and consolidation therapy for sarcoma was used (vincristine, adriamycin, cyclophosphamide, rifaphosphamide), with good response. The patient achieved clinical remission and 6 months later underwent an autologous bone marrow transplantation. One month after transplantation, the patient returned with fever, and the peripheral blood exhibited a white cell count of /L with 7% circulating blasts. Flow cytometry studies on peripheral blood detected blasts that expressed CD4, CD, and CD56, although other surface T- and B-cell markers were negative. Subsequently, sections from the original lymph node were stained for CD56 and found to be positive. Cytoreductive chemotherapy was instituted; however, the patient continued to deteriorate and died months after transplantation. Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al 4

2 Table. Immunohistologic Studies Antigen Antibody/Clone Source* Cell Reactivity Lymph Node CD CD4 CD8 CD0 CD0 CD4 CD4 CD45RO CD45RB CD56 CD57 CD68 CD79a CD99 Ki-67 MPO TIA- TdT Keratin Actin Desmin Chromogranin Synaptophysin S00 Endomysial antibody Polyclonal CD IF6 C8/44B L6 BerH MY0 Leu- A6 PD7/6 C HNK- KP JCB7 E7/MIC MIB- Myeloperoxidase NS/-AG4 Polyclonal AE (6,7) HHF5 D LKH0 SY8 Polyclonal EO T cells T helper/inducer, monocytes T suppressor/cytotoxic B cells Activated T and B cells Progenitor cells T cells, other T cells, monocytes, macrophages Leukocytes NK, NK-like T cells, neural NK, NK-like T cells, neural Myeloid, macrophage B cells Lymphoblastic, PNET Non G0-proliferating cells Myeloid, monocytes NK, T suppressor/cytotoxic Precursor T and B cells Epithelial Muscle Muscle Neuroendocrine Neuroendocrine Neural, melanocytic Epithelial Weakly positive Positive Positive Weakly positive 70% * indicates Dako Corporation, Carpinteria, Calif;, Novocastra, New Castle-Upon-Tyne, England;, Becton Dickinson, San Jose, Calif; 4, Coulter/Itek, Hialeah, Fla; 5, Immunotech, Cedex, France; 6, Monosan, Uden, The Netherlands; 7, Zymed, San Francisco, Calif; 8, Supertechs, Bethesda, Md; and 9, Boehringer Mannheim Biochemica, Indianapolis, Ind. NK indicates natural killer; PNET, peripheral neuroectodermal tumor. MATERIALS AND METHODS Morphologic Testing The lymph node biopsy specimen was fixed in 0% formalin, whereas the bone marrow core biopsy specimen was fixed in Bouin solution and subjected to brief decalcification and stained with hematoxylin-eosin. Peripheral blood smears were stained with Wright-Giemsa. Immunohistochemistry Primary antibodies are listed in Table. Sections of 4 m were cut, deparaffinized, and hydrated in a graded series of alcohol. Antigen retrieval by microwave procedure in citric acid buffer (0 mm, ph 6.0) for 0 minutes preceded staining for CD, CD8, CD0, CD0, CD4, CD45RB, CD56, CD68, CD79A, CD99, Ki- 67, TIA-I, and TdT. Microwave pretreatment for CD4 was carried out in EDTA buffer ( mm, ph 8.0). Stains for CD56 and TdT were performed using a modified biotin-streptavidin method. 9 All other stains were performed on an automated machine (Ventana Medical Systems Inc, Tucson, Ariz). Flow Cytometry Direct dual-parameter flow cytometry was performed on a FACscan (Becton Dickinson, San Jose, Calif) using standard whole blood lysis techniques. Commercially available fluorescein isothiocyanate or phycoerythrin-conjugated monoclonal antibodies were used (Table ). An analysis gate was selected to include the predominant population in the weak CD45 /low-side scatter region. The percentage of events reactive with each monoclonal antibody was determined, setting thresholds with isotypic controls. Positive expression was defined as greater than or equal to 0%. Cytoplasmic CD, CD79a, and MPO were assessed by flow cytometry using CalTag Fix/Perm reagents (CalTag Laboratories, An Der Grub, Austria). Cytogenetic Analysis The bone marrow aspirate was cultured and chromosomes were analyzed using the GTW banding method. 0 Twenty-two chromosome metaphases were analyzed. In Situ Hybridization for EBV EBER- RNA In situ hybridization was performed using a 0-base oligonucleotide probe complimentary to a portion of the EBER- gene as previously described. Heteroduplex Analysis of T-Cell Receptor Gene Rearrangement Amplification and heteroduplex polymerase chain reaction for T-cell receptor gene rearrangement was performed as previously described. Polymerase chain reaction amplification was performed in a Perkin Elmer 400 thermal cycler. RESULTS Morphologic Testing The cervical lymph node showed effaced architecture and a sheetlike proliferation of dyscohesive cells with extracapsular extension. The neoplastic cells were medium sized with scant cytoplasm, round to slightly oval nuclei, inconspicuous or small nucleoli, and finely granular chromatin. Mitotic figures were numerous ( 6 per high-power field), including atypical mitotic profiles. No glandular elements, rosettes, or strap cells were present (Figure, A). The bone marrow biopsy specimen was hypercellular (95%), with areas of normal trilineage hematopoiesis interspersed with paratrabecular and interstitial infiltrates of atypical blastlike cells, comprising 0% of the marrow space (Figure, B). No circulating blasts were identified at this time. The peripheral blood smear after transplantation showed 7% blasts consistent with relapse and progression to leukemia (Figure, C). Immunohistochemistry The neoplastic cells exhibited strong staining for CD4 and CD56 and weak staining for CD4 and CD99. They lacked reactivity for all other markers tested (Table and Figure ). 44 Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al

3 Table. Flow Cytometry Analysis Antigen Antibody/Clone Source* Specificity B lineage CD0 CD9 CD0 CD79a T lineage CD CD CD5 CD7 CD56 CD4/CD56 Myeloid lineage CD CD MPO CD4 CD64 CD6 Progenitor CD4 HLA-DR W8E7 J4.9 L7 HM SK7 SK7 L7F 4H9 MY L8 P67.6 MPO7 MOP9 FCGR- Y/5 HPCA- L4 CALLA, early lymphoid Pan-B Pan-B Cytoplasmic pan-b Surface immunoglobulin Surface immunoglobulin Mature T cells Surface, cytoplasmic pan-t Pan-T, CLL Early pan-t, NK, some AML NK, some T, AML and ALL Anomalous dual progenitor/nk Myeloid, monocytic Myeloid, monocytic Myeloid cytoplasmic protein Monocytic Monocytic, activated neutrophils Megakaryocytes, platelets Progenitor antigen Activation antigen Blood, % Positive * indicates Dako Corporation, Carpinteria, Calif;, Becton Dickinson, San Jose, Calif; and, Coulter/Itek, Hialeah, Fla. CALLA indicates common acute lymphoblastic leukemia antigen; CLL, chronic lymphocytic leukemia; NK, natural killer; AML, acute myeloid leukemia; and ALL, acute lymphoblastic leukemia. The percentage of events positive in weakly CD45-positive lymphoid low-light scatter analysis gate. 85 Figure. (A) Lymph node biopsy. Monomorphous infiltrate of medium-sized cells with scant cytoplasm, round nuclear contours, finely granular chromatin, and numerous mitotic figures (hematoxylin-eosin, original magnification 75); (B) Bone marrow core biopsy specimen. Hypercellular marrow with trilineage hematopoiesis and an interstitial infiltrate of immature blastlike cells (hematoxylin-eosin, original magnification 75). (C) Peripheral blood smear after bone marrow transplantation. Immature blasts with high nuclear-to-cytoplasmic ratio, agranular cytoplasm, and round nuclear contours (Wright-Giemsa, original magnification 500). Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al 45

4 Figure. Immunohistologic studies on lymph node sections show reactivity for CD56 and CD4 and lack reactivity for CD45 and TdT (original magnification 75). Flow Cytometry Posttransplantation peripheral blood sample showed a homogeneous population of cells, positive for CD4, CD56, CD, and cytoplasmic CD, whereas HLA-DR, surface CD, CD5, CD7, and CD were not expressed. Cytoplasmic CD79a and MPO were also not expressed (Table and Figure, A). Cytogenetic Studies Chromosomal analysis demonstrated an abnormal clone in of cells with the following karyotype: 46,XX,add()(p.),add(5)(q),add(8)(q). The rearrangements involving chromosomes, 5, and 8 were unbalanced and clonal. Additional nonclonal structural abnormalities were observed in 4 cells, of which showed apparent artifactual chromosomal loss. Although consistent with a malignant process, no diagnostic specificity is attributable to this karyotype (Figure, B). Studies for EBV and T-Cell Receptor Rearrangement There was no evidence of EBV messenger RNA or of a clonal T-cell receptor gene rearrangement. COMMENT Several unusual parameters contributed to the difficulty in making a diagnosis in this infant: young age, multiple masses without organomegaly or circulating blasts, and biopsy findings reminiscent of a small, round, blue cell tumor. The undifferentiated appearance of the neoplastic cells evoked a broad morphologic differential diagnosis that included peripheral neuroectodermal tumor/ewing sarcoma; neuroblastoma; Wilm tumor; congenital melanoma; rhabdomyosarcoma; desmoplastic, small, round cell tumor; and a blastic hematolymphoid malignancy. The initial panel of markers used for immunodiagnosis was extensive, although reactivity was present only for CD4, CD4, and CD99. But all markers for B-cell, T-cell, myeloid, and histiocytic differentiation, including CD45RB/leukocyte common antigen, were nonreactive. In addition, the patient s normal blood cell counts with absence of circulating blasts and partial nodular involvement rather than diffuse replacement of the marrow made the diagnosis of acute leukemia less likely. Although lack of TdT is unusual for LBL, given the undifferentiated morphologic features and lack of definitive markers, a blastic lymphoma was favored. The treatment choice for this patient reflected these diagnostic difficulties. Flow cytometry on peripheral blood at the time of relapse showed blasts expressing CD4, CD56, CD, and cytoplasmic CD. The absence of all B- and T-lineage markers, including surface CD7, CD9, CD, and cytoplasmic CD79a, did not support the diagnosis of early T- or B-cell precursor LBL/ALL. The definitive myeloid lineage antigen MPO was also absent. Cytoplasmic expres- 46 Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al

5 Figure. (A) Flow cytometry analysis of peripheral blood. Weak CD45 /low-side scatter region shows a population of cells with dual expression of CD56 and CD4 (upper left), absence of surface CD (upper right), presence of cytoplasmic CD and lack of MPO (lower left), and absence of CD and CD7 (lower right). (B) Karyotype of a neoplastic cell from the bone marrow. The karyotype reveals unbalanced abnormalities of the short arm of chromosome and the long arms of chromosomes 5 and 8. sion of CD subunits has been reported in precursor and activated NK cells. 6 In addition, the expression of CD56 but not CD57 on paraffin sections of the lymph node biopsy specimen indicates an immature NK phenotype. These results suggest an NK precursor acute leukemia. CD56 expression has been reported in approximately 0% of AML, especially those cases associated with translocation t(8;) or trisomy 8. 7 Leukemias postulated to arise from bipotential precursor cells (myeloid/nk cell acute leukemia) and a related entity with blastic cytologic features (myeloid/nk precursor acute leukemia) have also been reported.,8 Both these leukemias occur in a wide age range, spanning 8 to 7 years.,8 In addition, expression of CD56 in LBL 9 4 and in ALL 5 7 has also been reported. Most cases of LBL/ALL express TdT, whereas a few cases of NK precursor acute lymphoma/ leukemia are also known to express TdT. These findings indicate significant morphologic and immunophenotypic overlap between LBL/ALL and NK precursor malignancies, and their relation is currently under debate. Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al 47

6 Initial studies of blastic NK cell lymphoma/leukemia describe a distinct clinicopathologic entity of middle-aged and elderly patients with wide dissemination at presentation, absence of EBV, and an aggressive clinical course.,4,5,8,9 This entity has also been called acute undifferentiated leukemia by some authors. 6,0 Precursor NK malignancies, however, are rare in the pediatric age group. Three such cases occurring in children aged 4 to 7 years have been reported. 5,8, Transplacental transmission of an NK lymphoma has also been reported, although this case most likely represents a lymphoma derived from mature NK cells because no progenitor antigens were detected. To our knowledge, a lymphoma arising from NK precursors occurring in infancy has not been previously reported. Of interest is the lack of expression of CD7 in our case, which favors a diagnosis of blastic NK precursor acute lymphoma/leukemia over myeloid/nk precursor acute leukemia. In contrast, the expression of CD and CD4 favors myeloid/nk precursor acute leukemia. The patient in this study shows some features that overlap with both myeloid/nk precursor acute leukemia and blastic NK precursor acute lymphoma/leukemia,,5,8, and suggests that these entities may form a diagnostic continuum. The current case illustrates the need for a strong index of suspicion for recognition of this rare lymphoma/leukemia from solid tumors and other hematolymphoid neoplasms occurring in infancy that this disease may mimic. References. Jaffe ES, Krenacs L, Kumar S, et al. Extranodal peripheral T-cell and NK-cell neoplasms. Am J Clin Pathol. 999;:S46 S55.. Suzuki R, Yamamoto K, Seto M, et al. CD7 and CD56 myeloid/natural killer cell precursor acute leukemia: a distinct hematolymphoid disease entity. Blood. 997;90: Suzuki R, Nakamura S. Malignancies of natural killer (NK) cell precursor: myeloid/nk cell precursor acute leukemia and blastic NK cell lymphoma/leukemia. Leuk Res. 999;: DiGiuseppe JA, Louie DC, Williams JE, et al. Blastic natural killer cell leukemia/lymphoma: a clinicopathologic study. Am J Surg Pathol. 997;: Chan JK, Sin VC, Wong KF, et al. Nonnasal lymphoma expressing the natural killer cell marker CD56: a clinicopathologic study of 49 cases of an uncommon aggressive neoplasm. Blood. 997;89: Reuss-Borst MA, Jaschonek K, Muller CA. Acute undifferentiated leukemia with an unusual CD7 CD56 CD immunophenotype of NK progenitors. Leukemia. 996;0: Kawano S, Tatsumi E, Yoneda N, et al. Novel leukemic lymphoma with probable derivation from immature stage of natural killer (NK) lineage in an aged patient. Hematol Oncol. 995;:. 8. Gardiner CM, Reen DJ, O Meara A. Recognition of unusual presentation of natural killer cell leukemia. Am J Hematol. 995;50: Bindl JM Warnke RA. Advantages of detecting monoclonal antibody binding to tissue sections with biotin and avidin reagents in Coplin jars. Am J Clin Pathol. 986;85: Barch M. ACT Cytogenetics Laboratory Manual. nd ed. New York, NY: Raven Press; 99:.. van de Rijn M, Cleary ML, Variakojis D, et al. Epstein-Barr virus clonality in lymphomas occurring in patients with rheumatoid arthritis. Arthritis Rheum. 996;9: Natkunam Y, Smoller BR, Zehnder JL, et al. Aggressive cutaneous NK and NK-like T-cell lymphomas: clinicopathologic, immunohistochemical, and molecular analyses of cases. Am J Surg Pathol. 999;: Warnke RA, Weiss LM, Chan JKC, Cleary ML, Dorfman RF. Tumors of the Lymph Nodes and Spleen. Washington, DC: Armed Forces Institute of Pathology; 995. Atlas of Tumor Pathology; rd series, fascicle Chan JK, Tsang WY, Ng CS. Clarification of CD immunoreactivity in nasal T/natural killer cell lymphomas: the neoplastic cells are often CD epsilon. Blood. 996;87: Ho FC, Choy D, Loke SL, et al. Polymorphic reticulosis and conventional lymphomas of the nose and upper aerodigestive tract: a clinicopathologic study of 70 cases, and immunophenotypic studies of 6 cases. Hum Pathol. 990;: Lanier LL, Chang C, Spits H, et al. Expression of cytoplasmic CD epsilon proteins in activated human adult natural killer (NK) cells and CD gamma, delta, epsilon complexes in fetal NK cells: implications for the relationship of NK and T lymphocytes. J Immunol. 99;49: Suzumiya J, Takeshita M, Kimura N, et al. Expression of adult and fetal natural killer cell markers in sinonasal lymphomas. Blood. 994;8: Seymour JF, Pierce SA, Kantarjian HM, et al. Investigation of karyotypic, morphologic and clinical features in patients with acute myeloid leukemia blast cells expressing the neural cell adhesion molecule (CD56). Leukemia. 994;8: Scott AA, Head DR, Kopecky KJ, et al. HLA-DR-, CD, CD56, CD6- myeloid/natural killer cell acute leukemia: a previously unrecognized form of acute leukemia potentially misdiagnosed as French-American-British acute myeloid leukemia-m. Blood. 994;84: Swerdlow SH, Habeshaw JA, Richards MA, et al. T lymphoblastic lymphoma with LEU-7 positive phenotype and unusual clinical course: a multiparameter study. Leuk Res. 985;9: Sheibani K, Winberg CD, Burke JS, et al. Lymphoblastic lymphoma expressing natural killer cell-associated antigens: a clinicopathologic study of six cases. Leuk Res. 987;: Koita H, Suzumiya J, Ohshima K, et al. Lymphoblastic lymphoma expressing natural killer cell phenotype with involvement of the mediastinum and nasal cavity. Am J Surg Pathol. 997;: Ichinohasama R, Endoh K, Ishizawa K, et al. Thymic lymphoblastic lymphoma of committed natural killer cell precursor origin: a case report. Cancer. 996;77: Nakamura S, Koshikawa T, Yatabe Y, et al. Lymphoblastic lymphoma expressing CD56 and TdT. Am J Surg Pathol. 998;: Nakamura F, Tatsumi E, Kawano S, et al. Acute lymphoblastic leukemia/ lymphoblastic lymphoma of natural killer (NK) lineage: quest for another NKlineage neoplasm. Blood. 997;89: Brody JP, Allen S, Schulman P, et al. Acute agranular CD4-positive natural killer cell leukemia: comprehensive clinicopathologic studies including virologic and in vitro culture with inducing agents. Cancer. 995;75: Ichikawa M, Kawai H, Komiyama A, et al. Functional p75 interleukin- receptor expression on the fresh blast cells in childhood acute lymphoblastic leukemia with natural killer cell properties. Am J Hematol. 99;6: Pirruccello SJ, Bicak MS, Gordon BG, et al. Acute lymphoblastic leukemia of NK-cell lineage: responses to IL-. Leuk Res. 989;: Kobashi Y, Nakamura S, Sasajima Y, et al. Inconsistent association of Epstein-Barr virus with CD56 (NCAM)-positive angiocentric lymphoma occurring in sites other than the upper and lower respiratory tract. Histopathology. 996;8: Nakamura S, Suchi T, Koshikawa T, et al. Clinicopathologic study of CD56 (NCAM)-positive angiocentric lymphoma occurring in sites other than the upper and lower respiratory tract. Am J Surg Pathol. 995;9: Ino T, Tsuzuki M, Okamoto M, et al. Acute leukemia with the phenotype of a natural killer/t cell bipotential precursor. Ann Hematol. 999;78: Nagata T, Higashigawa M, Nagai M, et al. A child case of CD4, CD, HLA-DR, CD7, CD56 stem cell leukemia with thymic involvement. Leuk Res. 996;0: Arch Pathol Lab Med Vol 5, March 00 Natural Killer Cell Precursor Acute Lymphoma/Leukemia Natkunam et al