- Email: [email protected]
Z-138 cell line was derived from a patient with blastoid variant mantle cell lymphoma
Leukemia Research 30 (2006) 497–501
Brief communication
Z-138 cell line was derived from a patient with blastoid variant mantle cell lymphoma L. Jeffrey Medeiros a,∗ , Zeev Estrov b , George Z. Rassidakis a a
Department of Hematopathology, Box 72, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA b Department of Leukemia, The University of Texas, M.D. Anderson Cancer Center, Houston, Texas, USA Received 18 August 2005; received in revised form 22 August 2005; accepted 23 August 2005 Available online 3 October 2005
Abstract The Z-138 cell line, reported in the journal in 1998, was derived from a patient who developed a leukemia initially classified as chronic lymphocytic leukemia in 1987. Splenectomy for massive involvement was required in 1998 and the neoplasm subsequently transformed to an aggressive, mature B-cell leukemia 2 years later. At time of transformation, the neoplasm had a complex karyotype, including the t(11;14)(q13;q32). In light of the extensive updates in lymphoma classification that have occurred since that time, we reviewed the slides of the patient’s neoplasm. The initial peripheral blood and bone marrow aspirate smears and the spleen were involved by numerous small lymphocytes with mature chromatin. The last bone marrow specimen was involved by slightly larger, irregular lymphocytes with immature chromatin and a high mitotic rate. Immunohistochemical analysis performed on the spleen and last bone marrow for this report showed that the neoplastic cells over-expressed cyclin D1. According to the criteria of the current World Health Organization lymphoma classification, this neoplasm is best classified as mantle cell lymphoma, with blastoid transformation present in the terminal phase of disease. © 2005 Elsevier Ltd. All rights reserved. Keywords: Mantle cell lymphoma; Blastoid variant; Cell line; Cyclin D1
1. Introduction Estrov et al., in 1998, described the Z-138 cell line in the journal [1]. This cell line was derived from a patient who was initially diagnosed to have B-cell chronic lymphocytic leukemia and subsequently underwent morphologic transformation to an aggressive leukemia with L2 morphologic features. The neoplasm was of mature B-cell lineage and had a complex karyotype that included the t(11;14)(q13;q32) and an 8q− abnormality. The cell line retained these cytogenetic abnormalities, the 8q− was shown to be a t(8;14)(q24;q32), and Northern blot analysis showed cyclin D1 mRNA overexpression. Mantle cell lymphoma is a distinctive type of B-cell nonHodgkin lymphoma known to carry the t(11;14)(q13;q32) and over-express cyclin D1 [2]. Cyclin D1 plays an important ∗
Corresponding author. Tel.: +1 713 794 5446; fax: +1 713 745 0736. E-mail address: [email protected] (L.J. Medeiros).
0145-2126/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.leukres.2005.08.026
role during cell cycle progression from G1 to S phase. Prior to 1992, the term mantle cell lymphoma did not exist, nor was there consensus regarding the criteria for its diagnosis. Most often, tumors classified as mantle cell lymphoma were designated as centrocytic lymphoma, intermediately differentiated lymphocytic lymphoma, or mantle zone lymphoma. Recognition that the t(11;14) or bcl-1 locus rearrangements were common in these tumors [3,4] led to consensus criteria and the use of the term mantle cell lymphoma [5]. During the past 10 years, lymphoma classification has been extensively updated and entities are now defined on the basis of clinical, histologic, immunophenotypic, and molecular data. The current, widely accepted lymphoma classification, including criteria for mantle cell lymphoma and its variants, was published by the World Heath Organization (WHO) in 2001 [2]. In this report, we reviewed the slides of the patient whose neoplasm was the source of the Z-138 cell line. In retrospect, this patient’s neoplasm is best classified as mantle cell
498
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
lymphoma, presenting initially in leukemic phase, and subsequently undergoing transformation to blastoid variant.
2. Patient This patient was reported in detail previously [1]. Briefly, the patient was a 70-year-old man who had a 3-year clinical course. He initially presented in 1987 at a local hospital with marked leukocytosis and lymphocytosis, with a white blood cell (WBC) count of 83 × 109 /L and 90% small lymphocytes. The bone marrow was involved and the neoplasm was initially classified as B-cell chronic lymphocytic leukemia. The patient was treated with chlorambucil and prednisone with a poor clinical response, and subsequently was switched to cyclophosphamide, vincristine, and prednisone. One year later, the patient developed massive splenomegaly requiring splenectomy. Following splenectomy, the disease was under control for 18 months, but in 1990 the patient developed a WBC of 900 × 109 /L with 68% blasts. The blasts had a mature B-cell immunophenotype, positive for surface IgM, CD5, CD19, CD20, and HLA-DR, and negative for T-cell and myeloid antigens. Conventional cytogenetic studies showed a complex karyotype with two clones: 48,XY,+3,+13,8q−,t(11q−;14q+),t(14q+;18q−)[17]/49,XY, +3,+12,+13,8q−,t(11q−;14q+)t(14q+;18q−). Despite apheresis and chemotherapy, with temporary response, the patient recurred with central nervous system involvement and died of septicemia, 6 months later, 35 months after initial diagnosis. 2.1. Cell line The Z-138 cell line generated from this patient’s tumor was extensively characterized and reported previously [1]. The cells had numerous cytoplasmic vacuoles and the cytologic features were considered consistent with L3 type. The immunophenotype was very similar to the patient’s neoplasm except that the cells were reported to be CD5 negative. The karyotype of Z-138 was also similar to that of the patient’s neoplasm except that the 8q− was a der(8)t(8;14;?): 48,XY, der(8)t(8;14;?)(q24;q32;?), der(9) t(9;?) (q34;?), del(11) (q13; q25),+12,del(12)(q22q24.1), +13, der(14)t(8; 14;?) (q32;q21; ?),der(18)t(14;18;?)(q32;q21;?). Northern blot analysis showed high levels of cyclin D1 (PRAD1) mRNA but no evidence of bcl-1 locus rearrangement.
3. Results
Fig. 1. Peripheral blood smear prepared in 1987. The smear shows numerous small lymphocytes with dense chromatin and a smudge cell. The white blood cell count at this time was 83 × 109 /L. (Wright-Giemsa, 1000×).
“soccer ball” chromatin. A subset of cells, however, had small nucleoli or slightly increased cytoplasm with villous cytoplasmic projections. Bone marrow aspirate smears were hemodiluted but showed increased lymphocytes similar to those seen in the peripheral blood smear. The bone marrow aspirate clot section showed small particles, 60% cellular, with 50% small lymphocytes. A biopsy was not performed at this time. The splenectomy specimen from 1988 was massive and estimated to be approximately 3000 g. Histologically, the spleen had a vaguely nodular appearance, with neoplasm completely replacing the white pulp, with lesser involvement of the red pulp (Fig. 2). The neoplasm was composed of a monotonous proliferation of small lymphoid cells with round or slightly irregular nuclear contours. Mitotic figures were identified, but were less than 10 per 400× (high power) microscopic field (Olympus BX40 microscope, Leeds Instrument Co., Irving, TX). We retrospectively performed a cyclin D1 immunostain using the SP4 rabbit monoclonal antibody (LabVision, Fremont, CA) and an unstained section the spleen. The neoplastic cells are weakly to moderately positive. Only the core biopsy specimen is currently available from bone marrow specimen analyzed in 1990. The bone marrow is hypercellular, 80–90% with numerous small lymphoid cells in an interstitial and focally diffuse pattern (Fig. 3). In contrast with the other specimens, the lymphoid cells are slightly larger with more immature chromatin and irregular nuclear contours. Mitotic figures are easily identified, over 20 per 400× microscopic field. We retrospectively performed a cyclin D1 immunostain which showed that the neoplastic cells are strongly positive.
3.1. Reclassification of the patient’s neoplasm using the WHO system
3.2. Additional studies on the Z-138 cell line
The 1987 peripheral blood smear showed marked lymphocytosis (Fig. 1). The lymphocytes were small with relatively round nuclear contours and most cells had mature,
We performed limited flow cytometry immunophenotyping on Z-138 cells, including some markers that were not performed previously. The cells are positive for CD5 (par-
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
499
Fig. 2. Splenectomy specimen obtained in 1988. The spleen was 3000 g. (A) The neoplasm completely replaced the white pulp with lesser red pulp disease imparting a nodular appearance at low power magnification. (B) The neoplasm was composed of small lymphocytes. Cyclin D1, performed retrospectively, was weakly positive (not shown). (A) Hematoxylin-eosin, 100×. (B) Hematoxylin-eosin, 1000×.
tial and dim), CD20 (bright), CD23 (partial), and FMC7 (partial). Previously, CD5 was reported to be negative, perhaps explained by less sensitive methods of detection at that time [1]. Expression of bright CD20 and FMC7 are typically observed in mantle cell lymphoma. Partial or dim CD23 expression is unusual, but can occur in a subset of neoplasms [6]. We also performed Western blot analysis on Z-138 cells using an anti-cyclin D1 antibody (C-20, Santa Cruz Biotechnology, Santa Cruz, CA). These cells strongly express cyclin D1 protein at a level comparable to that of two other wellcharacterized mantle cell lymphoma cell lines, Mino and SP-53 (Fig. 4) [7]. Expression of cyclin D1 in Z-138 cells was also demonstrated by immunostaining performed on a paraffin-embedded cell block (Fig. 4). 4. Discussion The criteria for the diagnosis of mantle cell lymphoma, as published in the WHO classification, are now much better established than they were at the time this patient’s neoplasm
Fig. 3. Bone marrow biopsy specimen obtained in 1990. (A) The neoplasm had an interstitial pattern. (B) The neoplastic cells, in contrast with Figs. 1 and 2, have more irregular nuclear contours and immature chromatin. (C) Cyclin D1, performed retrospectively, is strongly positive. (A) Hematoxylin-eosin, 200×. (B) Hematoxylin-eosin, 1000×. (C) Immunohistochemistry with hematoxylin counterstain, 400×.
was diagnosed [2]. It is now recognized that mantle cell lymphoma can present in leukemic phase, most often mimicking chronic lymphocytic leukemia [4,8]. In these cases, despite the small cell morphology, the diagnosis of mantle cell lymphoma is based on the presence of cyclin D1 over-expression and the t(11;14) or ccnd-1/JH fusion signals shown by conventional cytogenetics or fluorescence in situ hybridization
500
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
Fig. 4. Western blot analysis shows high expression levels of cyclin D1 in Z-138 cells comparable with the levels of two other mantle cell lymphoma cell lines, Mino and SP-53. Jurkat, a T-acute lymphoblastic leukemia cell line, is known to express cyclin D1 faintly and serves as a control in these immonoblots. Cyclin D1 expression was confirmed by immunohistochemistry using a paraffin-embedded cell block of Z-138 cells and the same monoclonal antibody.
(FISH), respectively. At our hospital, we have seen other patients who presented with marked lymphocytosis, initially had clinically indolent disease, and were diagnosed at another institution as B-cell chronic lymphocytic leukemia. Subsequently, at the time of referral to our hospital, often for progressive disease, bone marrow or lymph node evaluation has shown mantle cell lymphoma. A small proportion of patients with mantle cell lymphoma in leukemic phase also have extremely prominent splenomegaly, as was the case in this patient [9,10]. Splenectomy in this subset of patients is reported to have therapeutic value [10]. Rarely, patients with mantle cell lymphoma in leukemic phase can present with numerous prolymphocytes resembling B-cell prolymphocytic leukemia, referred to as the prolymphocytoid variant of mantle cell lymphoma [11,12]. These patients also have prominent splenomegaly and minimal lymphadenopathy, further mimicking B-cell prolymphocytic leukemia clinically. Clues for the diagnosis of mantle cell lymphoma in these patients include the presence of a minor subset of cells in the peripheral blood smear that resemble mantle cell lymphoma cells, in addition to the numerous prolymphocytes, and the immunophenotype (mature B-cell, CD5+, and CD23−). The relationship between the prolymphocytic variant of mantle cell lymphoma and blastoid transformation is uncertain, but chromosome 17 abnormalities or p53 gene mutations have been described in a subset of these tumors [12,13]. It is also currently recognized that mantle cell lymphoma can undergo transformation to blastoid variant [2]. In tissue specimens, these neoplasms can resemble precursor Bcell lymphoblastic leukemia/lymphoma or large B-cell lymphoma [2]. In the blood and bone marrow, the resemblance to acute lymphoblastic leukemia can be particularly striking [2,8]. In blastoid variant, the neoplastic cells usually retain most of the immunophenotypic features of mantle cell lymphoma and carry the t(11;14). Other genetic abnormalities in blastoid mantle cell lymphoma are also common, including p53 and p16 gene mutations, as well as c-myc gene amplification or translocations [2,14]. In light of the WHO classification, and with the benefit of hindsight, we decided to review the histologic slides of the neoplasm from which the Z-138 cell line was derived. Although the 1987 peripheral blood and bone marrow specimens are morphologically indistinguishable from B-cell
chronic lymphocytic leukemia, the histologic findings in the 1988 spleen and 1990 bone marrow biopsy specimens are most consistent with mantle cell lymphoma, with the 1990 specimen being the blastoid variant. This conclusion is supported by the mature B-cell immunophenotype, the positive cyclin D1 immunostains performed on the 1998 spleen and 1990 bone marrow specimens, and the conventional cytogenetic findings showing the t(11;14) in the 1990 bone marrow specimen. This conclusion is further supported by the demonstration of cyclin D1 over-expression in Z-138 cells by three independent methods (Northern and Western blotting and immunohistochemistry). The reclassification of this patient’s neoplasm as blastoid variant mantle cell lymphoma should be helpful to authors of future studies in which the Z-138 cell line is used.
Acknowledgements This manuscript is the work of the authors who have no conflict of interest and no financial support. Contributions. L. Jeffrey Medeiros contributed to the case and material collection, re-evaluation of patient’s specimens, and preparation of the manuscript. Zeev Estrov generated the cell line and contributed to the preparation of the manuscript. George Z. Rassidakis contributed laboratory data and also contributed to preparation of the manuscript.
References [1] Estrov Z, Talpaz M, Ku S, Harris D, Van Q, Beran M, et al. Z-138: a new mature B-cell acute lymphoblastic leukemia cell line from a patient with transformed chronic lymphocytic leukemia. Leuk Res 1998;22:341–53. [2] Swerdlow SH, Berger F, Isaacson PI, Muller-Hermelink HK, Nathwani BN, Piris MA, et al. Mantle cell lymphoma. In: Jaffe ES, Harris NL, Stein H, Vardiman JW, editors. World Health Organization Classification of Tumours. Pathology and genetics of tumours of haematopoietic and lymphoid tissues. Lyon: IARC Press; 2001. p. 168–70. [3] Williams ME, Westermann CD, Swerdlow SH. Genotypic characterization of centrocytic lymphoma: frequent rearrangement of the chromosome 11 bcl-1 locus. Blood 1990;76:1387–91. [4] Medeiros LJ, Van Krieken JH, Jaffe ES, Raffeld M. Association of bcl-1 rearrangements with lymphocytic lymphoma of intermediate differentiation. Blood 1990;76:2086–90.
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501 [5] Banks PM, Chan J, Cleary ML, Delsol G, De Wolf-Peeters C, Gatter K, et al. Mantle cell lymphoma. A proposal for unification of morphologic, immunologic, and molecular data. Am J Surg Pathol 1992;16:637–40. [6] Schlette E, Fu K, Medeiros LJ. CD23 expression in mantle cell lymphoma: clinicopathologic features of 18 cases. Am J Clin Pathol 2003;120:760–6. [7] Amin HM, McDonnell TJ, Medeiros LJ, Rassidakis GZ, Leventaki V, O’Connor SL, et al. Characterization of 4 mantle cell lymphoma cell lines. Arch Pathol Lab Med 2003;127:424–31. [8] Schlette E, Lai R, Onciu M, Doherty D, Bueso-Ramos C, Medeiros LJ. Leukemia mantle cell lymphoma: clinical and pathologic spectrum of twenty-three cases. Mod Pathol 2001;14:1133–40. [9] Molina TJ, Delmer A, Cymbalista F, Le Tourneau A, Perrot JY, Ramond S, et al. Mantle cell lymphoma in leukaemic phase with prominent splenomegaly. A report of eight cases with similar clinical presentation and aggressive outcome. Virchows Arch 2000;437:591–8.
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[10] Angelopoulou MK, Siakantaris MP, Vassilakopoulos TP, Kontopidou FN, Rassidakis GZ, Dimopoulou MN, et al. The splenic form of mantle cell lymphoma. Eur J Haematol 2002;68:12–21. [11] Schlette E, Bueso-Ramos C, Giles F, Glassman A, Hayes K, Medeiros LJ. Mature B-cell leukemias with more than 55% prolymphocytes. A heterogeneous group that includes an unusual variant of mantle cell lymphoma. Am J Clin Pathol 2001;115:571– 81. [12] Ruchlemer R, Parry-Jones N, Brito-Babapulle V, Wotherspoon AC, Matutes E, Catovsky D. B-prolymphocytic leukaemia with t(11;14) revisited: a splenomegalic form of mantle cell lymphoma evolving with leukaemia. Br J Haematol 2004;125:330–6. [13] Khoury JD, Sen F, Abruzzo LV, Hayes K, Glassman A, Medeiros LJ. Cytogenetic findings in blastoid mantle cell lymphoma. Hum Pathol 2003;34:1022–9. [14] Hao S, Sanger W, Onciu M, Lai R, Schlette EJ, Medeiros LJ. Mantle cell lymphoma with 8q24 chromosomal abnormalities: a report of 5 cases with blastoid features. Mod Pathol 2002;15:1266–72.
Brief communication
Z-138 cell line was derived from a patient with blastoid variant mantle cell lymphoma L. Jeffrey Medeiros a,∗ , Zeev Estrov b , George Z. Rassidakis a a
Department of Hematopathology, Box 72, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA b Department of Leukemia, The University of Texas, M.D. Anderson Cancer Center, Houston, Texas, USA Received 18 August 2005; received in revised form 22 August 2005; accepted 23 August 2005 Available online 3 October 2005
Abstract The Z-138 cell line, reported in the journal in 1998, was derived from a patient who developed a leukemia initially classified as chronic lymphocytic leukemia in 1987. Splenectomy for massive involvement was required in 1998 and the neoplasm subsequently transformed to an aggressive, mature B-cell leukemia 2 years later. At time of transformation, the neoplasm had a complex karyotype, including the t(11;14)(q13;q32). In light of the extensive updates in lymphoma classification that have occurred since that time, we reviewed the slides of the patient’s neoplasm. The initial peripheral blood and bone marrow aspirate smears and the spleen were involved by numerous small lymphocytes with mature chromatin. The last bone marrow specimen was involved by slightly larger, irregular lymphocytes with immature chromatin and a high mitotic rate. Immunohistochemical analysis performed on the spleen and last bone marrow for this report showed that the neoplastic cells over-expressed cyclin D1. According to the criteria of the current World Health Organization lymphoma classification, this neoplasm is best classified as mantle cell lymphoma, with blastoid transformation present in the terminal phase of disease. © 2005 Elsevier Ltd. All rights reserved. Keywords: Mantle cell lymphoma; Blastoid variant; Cell line; Cyclin D1
1. Introduction Estrov et al., in 1998, described the Z-138 cell line in the journal [1]. This cell line was derived from a patient who was initially diagnosed to have B-cell chronic lymphocytic leukemia and subsequently underwent morphologic transformation to an aggressive leukemia with L2 morphologic features. The neoplasm was of mature B-cell lineage and had a complex karyotype that included the t(11;14)(q13;q32) and an 8q− abnormality. The cell line retained these cytogenetic abnormalities, the 8q− was shown to be a t(8;14)(q24;q32), and Northern blot analysis showed cyclin D1 mRNA overexpression. Mantle cell lymphoma is a distinctive type of B-cell nonHodgkin lymphoma known to carry the t(11;14)(q13;q32) and over-express cyclin D1 [2]. Cyclin D1 plays an important ∗
Corresponding author. Tel.: +1 713 794 5446; fax: +1 713 745 0736. E-mail address: [email protected] (L.J. Medeiros).
0145-2126/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.leukres.2005.08.026
role during cell cycle progression from G1 to S phase. Prior to 1992, the term mantle cell lymphoma did not exist, nor was there consensus regarding the criteria for its diagnosis. Most often, tumors classified as mantle cell lymphoma were designated as centrocytic lymphoma, intermediately differentiated lymphocytic lymphoma, or mantle zone lymphoma. Recognition that the t(11;14) or bcl-1 locus rearrangements were common in these tumors [3,4] led to consensus criteria and the use of the term mantle cell lymphoma [5]. During the past 10 years, lymphoma classification has been extensively updated and entities are now defined on the basis of clinical, histologic, immunophenotypic, and molecular data. The current, widely accepted lymphoma classification, including criteria for mantle cell lymphoma and its variants, was published by the World Heath Organization (WHO) in 2001 [2]. In this report, we reviewed the slides of the patient whose neoplasm was the source of the Z-138 cell line. In retrospect, this patient’s neoplasm is best classified as mantle cell
498
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
lymphoma, presenting initially in leukemic phase, and subsequently undergoing transformation to blastoid variant.
2. Patient This patient was reported in detail previously [1]. Briefly, the patient was a 70-year-old man who had a 3-year clinical course. He initially presented in 1987 at a local hospital with marked leukocytosis and lymphocytosis, with a white blood cell (WBC) count of 83 × 109 /L and 90% small lymphocytes. The bone marrow was involved and the neoplasm was initially classified as B-cell chronic lymphocytic leukemia. The patient was treated with chlorambucil and prednisone with a poor clinical response, and subsequently was switched to cyclophosphamide, vincristine, and prednisone. One year later, the patient developed massive splenomegaly requiring splenectomy. Following splenectomy, the disease was under control for 18 months, but in 1990 the patient developed a WBC of 900 × 109 /L with 68% blasts. The blasts had a mature B-cell immunophenotype, positive for surface IgM, CD5, CD19, CD20, and HLA-DR, and negative for T-cell and myeloid antigens. Conventional cytogenetic studies showed a complex karyotype with two clones: 48,XY,+3,+13,8q−,t(11q−;14q+),t(14q+;18q−)[17]/49,XY, +3,+12,+13,8q−,t(11q−;14q+)t(14q+;18q−). Despite apheresis and chemotherapy, with temporary response, the patient recurred with central nervous system involvement and died of septicemia, 6 months later, 35 months after initial diagnosis. 2.1. Cell line The Z-138 cell line generated from this patient’s tumor was extensively characterized and reported previously [1]. The cells had numerous cytoplasmic vacuoles and the cytologic features were considered consistent with L3 type. The immunophenotype was very similar to the patient’s neoplasm except that the cells were reported to be CD5 negative. The karyotype of Z-138 was also similar to that of the patient’s neoplasm except that the 8q− was a der(8)t(8;14;?): 48,XY, der(8)t(8;14;?)(q24;q32;?), der(9) t(9;?) (q34;?), del(11) (q13; q25),+12,del(12)(q22q24.1), +13, der(14)t(8; 14;?) (q32;q21; ?),der(18)t(14;18;?)(q32;q21;?). Northern blot analysis showed high levels of cyclin D1 (PRAD1) mRNA but no evidence of bcl-1 locus rearrangement.
3. Results
Fig. 1. Peripheral blood smear prepared in 1987. The smear shows numerous small lymphocytes with dense chromatin and a smudge cell. The white blood cell count at this time was 83 × 109 /L. (Wright-Giemsa, 1000×).
“soccer ball” chromatin. A subset of cells, however, had small nucleoli or slightly increased cytoplasm with villous cytoplasmic projections. Bone marrow aspirate smears were hemodiluted but showed increased lymphocytes similar to those seen in the peripheral blood smear. The bone marrow aspirate clot section showed small particles, 60% cellular, with 50% small lymphocytes. A biopsy was not performed at this time. The splenectomy specimen from 1988 was massive and estimated to be approximately 3000 g. Histologically, the spleen had a vaguely nodular appearance, with neoplasm completely replacing the white pulp, with lesser involvement of the red pulp (Fig. 2). The neoplasm was composed of a monotonous proliferation of small lymphoid cells with round or slightly irregular nuclear contours. Mitotic figures were identified, but were less than 10 per 400× (high power) microscopic field (Olympus BX40 microscope, Leeds Instrument Co., Irving, TX). We retrospectively performed a cyclin D1 immunostain using the SP4 rabbit monoclonal antibody (LabVision, Fremont, CA) and an unstained section the spleen. The neoplastic cells are weakly to moderately positive. Only the core biopsy specimen is currently available from bone marrow specimen analyzed in 1990. The bone marrow is hypercellular, 80–90% with numerous small lymphoid cells in an interstitial and focally diffuse pattern (Fig. 3). In contrast with the other specimens, the lymphoid cells are slightly larger with more immature chromatin and irregular nuclear contours. Mitotic figures are easily identified, over 20 per 400× microscopic field. We retrospectively performed a cyclin D1 immunostain which showed that the neoplastic cells are strongly positive.
3.1. Reclassification of the patient’s neoplasm using the WHO system
3.2. Additional studies on the Z-138 cell line
The 1987 peripheral blood smear showed marked lymphocytosis (Fig. 1). The lymphocytes were small with relatively round nuclear contours and most cells had mature,
We performed limited flow cytometry immunophenotyping on Z-138 cells, including some markers that were not performed previously. The cells are positive for CD5 (par-
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
499
Fig. 2. Splenectomy specimen obtained in 1988. The spleen was 3000 g. (A) The neoplasm completely replaced the white pulp with lesser red pulp disease imparting a nodular appearance at low power magnification. (B) The neoplasm was composed of small lymphocytes. Cyclin D1, performed retrospectively, was weakly positive (not shown). (A) Hematoxylin-eosin, 100×. (B) Hematoxylin-eosin, 1000×.
tial and dim), CD20 (bright), CD23 (partial), and FMC7 (partial). Previously, CD5 was reported to be negative, perhaps explained by less sensitive methods of detection at that time [1]. Expression of bright CD20 and FMC7 are typically observed in mantle cell lymphoma. Partial or dim CD23 expression is unusual, but can occur in a subset of neoplasms [6]. We also performed Western blot analysis on Z-138 cells using an anti-cyclin D1 antibody (C-20, Santa Cruz Biotechnology, Santa Cruz, CA). These cells strongly express cyclin D1 protein at a level comparable to that of two other wellcharacterized mantle cell lymphoma cell lines, Mino and SP-53 (Fig. 4) [7]. Expression of cyclin D1 in Z-138 cells was also demonstrated by immunostaining performed on a paraffin-embedded cell block (Fig. 4). 4. Discussion The criteria for the diagnosis of mantle cell lymphoma, as published in the WHO classification, are now much better established than they were at the time this patient’s neoplasm
Fig. 3. Bone marrow biopsy specimen obtained in 1990. (A) The neoplasm had an interstitial pattern. (B) The neoplastic cells, in contrast with Figs. 1 and 2, have more irregular nuclear contours and immature chromatin. (C) Cyclin D1, performed retrospectively, is strongly positive. (A) Hematoxylin-eosin, 200×. (B) Hematoxylin-eosin, 1000×. (C) Immunohistochemistry with hematoxylin counterstain, 400×.
was diagnosed [2]. It is now recognized that mantle cell lymphoma can present in leukemic phase, most often mimicking chronic lymphocytic leukemia [4,8]. In these cases, despite the small cell morphology, the diagnosis of mantle cell lymphoma is based on the presence of cyclin D1 over-expression and the t(11;14) or ccnd-1/JH fusion signals shown by conventional cytogenetics or fluorescence in situ hybridization
500
L.J. Medeiros et al. / Leukemia Research 30 (2006) 497–501
Fig. 4. Western blot analysis shows high expression levels of cyclin D1 in Z-138 cells comparable with the levels of two other mantle cell lymphoma cell lines, Mino and SP-53. Jurkat, a T-acute lymphoblastic leukemia cell line, is known to express cyclin D1 faintly and serves as a control in these immonoblots. Cyclin D1 expression was confirmed by immunohistochemistry using a paraffin-embedded cell block of Z-138 cells and the same monoclonal antibody.
(FISH), respectively. At our hospital, we have seen other patients who presented with marked lymphocytosis, initially had clinically indolent disease, and were diagnosed at another institution as B-cell chronic lymphocytic leukemia. Subsequently, at the time of referral to our hospital, often for progressive disease, bone marrow or lymph node evaluation has shown mantle cell lymphoma. A small proportion of patients with mantle cell lymphoma in leukemic phase also have extremely prominent splenomegaly, as was the case in this patient [9,10]. Splenectomy in this subset of patients is reported to have therapeutic value [10]. Rarely, patients with mantle cell lymphoma in leukemic phase can present with numerous prolymphocytes resembling B-cell prolymphocytic leukemia, referred to as the prolymphocytoid variant of mantle cell lymphoma [11,12]. These patients also have prominent splenomegaly and minimal lymphadenopathy, further mimicking B-cell prolymphocytic leukemia clinically. Clues for the diagnosis of mantle cell lymphoma in these patients include the presence of a minor subset of cells in the peripheral blood smear that resemble mantle cell lymphoma cells, in addition to the numerous prolymphocytes, and the immunophenotype (mature B-cell, CD5+, and CD23−). The relationship between the prolymphocytic variant of mantle cell lymphoma and blastoid transformation is uncertain, but chromosome 17 abnormalities or p53 gene mutations have been described in a subset of these tumors [12,13]. It is also currently recognized that mantle cell lymphoma can undergo transformation to blastoid variant [2]. In tissue specimens, these neoplasms can resemble precursor Bcell lymphoblastic leukemia/lymphoma or large B-cell lymphoma [2]. In the blood and bone marrow, the resemblance to acute lymphoblastic leukemia can be particularly striking [2,8]. In blastoid variant, the neoplastic cells usually retain most of the immunophenotypic features of mantle cell lymphoma and carry the t(11;14). Other genetic abnormalities in blastoid mantle cell lymphoma are also common, including p53 and p16 gene mutations, as well as c-myc gene amplification or translocations [2,14]. In light of the WHO classification, and with the benefit of hindsight, we decided to review the histologic slides of the neoplasm from which the Z-138 cell line was derived. Although the 1987 peripheral blood and bone marrow specimens are morphologically indistinguishable from B-cell
chronic lymphocytic leukemia, the histologic findings in the 1988 spleen and 1990 bone marrow biopsy specimens are most consistent with mantle cell lymphoma, with the 1990 specimen being the blastoid variant. This conclusion is supported by the mature B-cell immunophenotype, the positive cyclin D1 immunostains performed on the 1998 spleen and 1990 bone marrow specimens, and the conventional cytogenetic findings showing the t(11;14) in the 1990 bone marrow specimen. This conclusion is further supported by the demonstration of cyclin D1 over-expression in Z-138 cells by three independent methods (Northern and Western blotting and immunohistochemistry). The reclassification of this patient’s neoplasm as blastoid variant mantle cell lymphoma should be helpful to authors of future studies in which the Z-138 cell line is used.
Acknowledgements This manuscript is the work of the authors who have no conflict of interest and no financial support. Contributions. L. Jeffrey Medeiros contributed to the case and material collection, re-evaluation of patient’s specimens, and preparation of the manuscript. Zeev Estrov generated the cell line and contributed to the preparation of the manuscript. George Z. Rassidakis contributed laboratory data and also contributed to preparation of the manuscript.
References [1] Estrov Z, Talpaz M, Ku S, Harris D, Van Q, Beran M, et al. Z-138: a new mature B-cell acute lymphoblastic leukemia cell line from a patient with transformed chronic lymphocytic leukemia. Leuk Res 1998;22:341–53. [2] Swerdlow SH, Berger F, Isaacson PI, Muller-Hermelink HK, Nathwani BN, Piris MA, et al. Mantle cell lymphoma. In: Jaffe ES, Harris NL, Stein H, Vardiman JW, editors. World Health Organization Classification of Tumours. Pathology and genetics of tumours of haematopoietic and lymphoid tissues. Lyon: IARC Press; 2001. p. 168–70. [3] Williams ME, Westermann CD, Swerdlow SH. Genotypic characterization of centrocytic lymphoma: frequent rearrangement of the chromosome 11 bcl-1 locus. Blood 1990;76:1387–91. [4] Medeiros LJ, Van Krieken JH, Jaffe ES, Raffeld M. Association of bcl-1 rearrangements with lymphocytic lymphoma of intermediate differentiation. Blood 1990;76:2086–90.
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