BCL6 Rearrangement and Mediastinal Involvement in a Case of B Cell Acute Lymphoblastic Leukemia

BCL6 rearrangement and mediastinal involvement in a case of B cell acute lymphoblastic leukemia

TO THE EDITOR

A quarter of children with non-Hodgkin’s lymphoma (NHL) present with anterior mediastinal masses, the majority of which have lymphoblastic histology with a T cell origin.1–3 Approximately 15% of patients with mediastinal NHL have tumors of nonlymphoblastic type, including large cell immunoblastic lymphomas and rare cases of undifferentiated non- Burkitt lymphoma.1–3 However, Burkitt lymphomas presenting in the mediastinum are exceedingly rare. Here we report a patient with B cell acute lymphoblastic leukemia (ALL) who presented with an anterior mediastinal mass. In addition, this patient demonstrated an atypical pattern of surface antigens and an unusual karyotype. A 9-year-old girl presented with a 3-week history of inter- mittent fever, decreased appetite, fatigue, occasional left chest pain, mild cough and orthopnea. One day prior to being transferred to St Jude Children’s Research Hospital, she was seen by a local physician who noted a large mediastinal mass on chest X-ray and a leukocyte count of 20 × 109/l with circulat- ing blasts. The physical examination on admission was significant only for decreased breath sounds over the left chest and enlarge- ment of the liver and spleen. Initial laboratory results showed the following values: hemoglobin, 10.7 g/dl; platelet count, 207 × 109/l; leukocyte count, 15.2 × 109/l with a differential of 30% segmented neutrophils, 3% bands, 49% lymphocytes, 3% monocytes, 2% eosinophils, 6% myelocytes, 4% meta- myelocytes, and 3% blasts. Blood chemistries were normal except for a uric acid of 8.8 mg/dl and lactate dehydrogenase of 14 747 U/l. Following the diagnostic workup described below, the patients was treated according to the LMB89 regimen.4 She had a slow response to therapy, relapsed 4 months from diagnosis, and died of progressive disease 2 months later. Posteroanterior chest radiograph at presentation showed a large mediastinal mass with shift of the mediastinum to the right of the midline and a left pleural effusion (Figure 1a). Computed tomographic (CT) imaging of the chest demonstrated a large inhomogeneously enhancing anterior mediastinal mass with displacement of the great vessels and left sub- clavian vein posteriorly, as well as compression of the left lung (Figure 1b). CT imaging of the abdomen was normal. Bone marrow aspirate at presentation revealed hypercellu- lar spicules with infiltrate of moderately large blasts with abundant deep blue vacuolated cytoplasm, moderately large regular nuclei, and several indistinct nucleoli (Figure 2), fea- Figure 1 Imaging studies at diagnosis. (a) Posteroanterior chest radiograph shows mediastinal shift to the right of midline by both the tures of L3-ALL. The blasts were negative for myeloperoxid- left pleural effusion (long arrows) and the mediastinal mass. The left ase, Sudan black and ␣-naphthyl butyrate esterase. By flow lateral margin of the mass is outlined by a small portion of aerated cytometric analysis, the leukemic blasts were positive for left lung (short arrows). (b) Axial contrast-enhanced computed tomographic image of the chest demonstrates the large inhomogeneously enhancing anterior mediastinal mass which has displaced the great vessels (arrows) far posteriorly. Also seen are narrowing of the left Correspondence: JE Rubnitz, Department of Hematology/Oncology, mainstem bronchus and left lung, as well as an associated left St Jude Children’s Research Hospital, 332 N Lauderdale Street, pleural effusion. Memphis, TN 38105-2794, USA; Fax: 901 521 9005 Received 16 February 1998; accepted 11 March 1998 Correspondence 1164

Figure 2 Bone marrow aspirate at presentation. Marrow was effaced by an inﬁltrate of large blasts with abundant deep blue vacuolated cytoplasm, moderately large regular nuclei, and several indistinct nucleoli.

HLA-DR, CD45, CD10, CD19, CD20, CD21, CD22, and surface immunoglobulin heavy chain alpha. The blasts did not express TdT or CD34. All T cell and myeloid markers were negative. In addition, there was no detectable cytoplasmic or surface immunoglobulin mu, kappa, lambda, delta, or gamma. Chromosome analysis revealed one abnormal stem line with the following karyotype: 46,XX,t(3;22)(q27;q11), t(8;14)(q24;q32). Southern blot analysis was performed on genomic DNA iso- Figure 3 Southern blot analysis of patient and control DNAs. lated from the patient’s leukemic blasts to investigate the Samples were digested with BamHI (B) and XbaI (X) and hybridized with a BCL6-specific probe. The patient sample revealed an abnormal status of the BCL6, immunoglobulin heavy chain, and c-MYC ␮ 6.6-kb restriction fragment (lane 2) representing rearrangement of genes. Briefly, 10 g of DNA was digested with various BCL6. Molecular weight markers (M) are shown on the right. restriction enzymes, separated electrophoretically in 0.8% agarose gels, and transferred to nylon membranes. Hybridiz- ation of XbaI-digested DNA with a BCL6-specific probe (Sac stinal lymphoma with typical Burkitt morphology were 4.0 probe, kindly provided by Dr R Dalla-Favera, Columbia reported. Clinical studies of B cell lymphoma and ALL also University, New York) revealed an abnormal 6.6 kb restriction demonstrate a lack of mediastinal Burkitt lymphoma. In one fragment (Figure 3), representing rearrangement of BCL6. study of 216 B cell patients, only two had disease in the Digests with BamHI/HindIII, BglII, and XbaI demonstrated two chest.5 Similarly, no cases of mediastinal disease were rearranged mu chain genes (data not shown) when probed reported among 87 cases of B cell ALL treated on BFM trials.6 with IghHJ6 (Dako, Carpinteria, CA, USA). A rearranged c- The case described here demonstrates the unusual occur- MYC gene was detected in blots of DNA digested with EcoRI, rence of B cell ALL presenting as a mediastinal mass and XbaI and HindIII (data not shown) using a cDNA probe to emphasizes the need for a complete diagnostic evaluation of exon 1 of c-MYC (HP132; Oncogene Research, Cambridge, all mediastinal masses. Although this patient was initially MA, USA). thought to have lymphoblastic lymphoma with bone marrow involvement, her bone marrow aspirate showed the presence of FAB-L3 lymphoblasts. Further studies demonstrated surface Discussion immunoglobulin heavy chains, c-MYC rearrangement, and t(8;14)(q24;q32), confirming the diagnosis of B cell leukemia. Children with NHL often present with extranodal disease, with The presence of surface alpha immunoglobulin heavy 26% of cases involving the mediastinum.1 Although most of chains without detectable kappa or lambda light is an unex- these cases are associated with lymphoblastic histology, 5% pected finding in Burkitt lymphoma. One potential expla- of NHL cases may present as primary mediastinal nonlym- nation is that the phenotype in this case was actually tran- phoblastic lymphoma.2 However, Burkitt lymphoma of the sitional pre-B and expressed surrogate light chains.7,8 mediastinum is rare. A review of 25 cases of mediastinal non- However, expression of surrogate light chains has not been lymphoblastic lymphoma revealed large cell immunoblastic reported in association with alpha heavy chains. In addition, histology in 20 cases, intermediate grade tumors in four cases, the polyclonal lambda antibody used here will detect surro- and small noncleaved non-Burkitt histology without bone gate lambda light chain. Other possible explanations for the marrow involvement in one case.2 Another pathologic review absence of light chains include the absence of kappa or of 48 cases of mediastinal NHL treated on Children’s Cancer lambda protein because of defective transcription or trans- Group protocols demonstrated lymphoblastic histology in 40 lation of light chain mRNA, use of insensitive assays for light cases, large cell lymphoma in five cases, and non-Burkitt pleo- chain expression, or inability of the antibodies used to recog- morphic histology in three cases.3 Again, no cases of media- nize truncated or defective light chain proteins. Under normal Correspondence 1165 conditions, binding of alpha heavy chains to the surface of B References cells requires the presence of kappa or lambda light chains. 1 Sandlund JT, Downing JR, Crist WM. Non-Hodgkin’s lymphoma Thus, it seems unlikely that kappa or lambda light chain genes in childhood. New Engl J Med 1996; 334: 1238–1248. were not rearranged and transcribed. Lack of detectable 2 Bunin NJ, Hvizdala E, Link M, Callihan TR, Hustu HO, Wharam immunoglobulin due to an insensitive assay is also unlikely, M, Warnke RA, Berard CW, Murphy SB. Mediastinal nonlym- because polyclonal immunoglobulin antisera of high quality phoblastic lymphomas in children: a clinicopathologic study. J from two different sources were used in flow cytometric analy- Clin Oncol 1986; 4: 154–159. 3 Wilson JF, Jenkin RD, Anderson JR, Chilcote RR, Coccia P, Exelby sis. Hence, conceivably this case had a truncated or defective PR, Kersey J, Kjeldsberg CR, Kushner J, Meadows A. Studies on kappa or lambda light chain that was not recognized by the the pathology of non-Hodgkin’s lymphoma of childhood. I. The polyclonal antibodies. role of routine histopathology as a prognostic factor. A report from Of greater interest, the leukemic clone in this case con- the Children’s Cancer Study Group. Cancer 1984; 53: 1695–1704. tained, in addition to the t(8;14), the t(3;22)(q27;q11), a trans- 4 Patte C, Michon J, Behrendt H, Leverger G, Bergeron C, Robert location that has previously been reported in diffuse large cell A, Mechinaud F, Bertrand Y, Perel Y, Coze C, Nelken B. Results of the LMB 89 protocol for childhood B cell lymphoma and leukemia lymphomas and follicular lymphomas, but not in Burkitt lym- (ALL). Study of the SFOP. Med Pediatr Oncol 1997; 24: 358. 6,9,10 phoma. In diffuse large cell lymphoma, the t(3;22) dis- 5 Patte C, Philip T, Rodary C, Zucker JM, Behrendt H, Gentet JC, rupts the BCL6 proto-oncogene in its 5Ј noncoding region, Lamagnere JP, Otten J, Dufillot D, Pein F et al. High survival rate leading to deregulated protein expression.11–14 Rearrange- in advanced-stage B cell lymphomas and leukemias without CNS ments of BCL6 have been reported most often in diffuse large involvement with a short intensive polychemotherapy: results from cell lymphoma, but are also seen, albeit at a lower frequency, the French Pediatric Oncology Society of a randomized trial of 216 children. J Clin Oncol 1991; 9: 123–132. in follicular lymphoma. BCL6 rearrangements have not been 6 Reiter A, Schrappe M, Ludwig WD, Lampert F, Harbott J, Henze reported in other types of NHL or in ALL. Southern blot analy- G, Niemeyer CM, Gadner H, Muller-Weihrich S, Ritter J et al. sis of the case presented here revealed clear evidence of BCL6 Favorable outcome of B cell acute lymphoblastic leukemia in rearrangement, which occurred as a consequence of translo- childhood: a report of three consecutive studies of the BFM group. cation to site of the ␭ light chain gene (3q27). This novel case, Blood 1992; 80: 2471–2478. therefore, demonstrates BCL6 involvement in B cell ALL, as 7 Lassoued K, Nunez CA, Billips L, Kubagawa H, Monteiro RC, LeBien TW, Cooper MD. Expression of surrogate light chain recep- well as rearrangement of BCL6 and c-MYC in the same clone. tors is restricted to a late stage in pre-B cell differentiation. Cell Although the simultaneous occurrence of the t(3;22) and 1993; 73: 73–86. t(8;14) has not been previously reported, two translocations 8 Koehler M, Behm FG, Shuster J, Crist W, Borowitz M, Look AT, involving the immunoglobulin genes may occur concurrently. Head D, Carroll AJ, Land V, Steuber P et al. Transitional pre-B For example, the t(3;22) may occur in cases of follicular lym- cell acute lymphoblastic leukemia of childhood is associated with phoma that also carry the t(14;18)10 and cell lines that harbor favorable prognostic clinical features and an excellent outcome: a 15 Pediatric Oncology Group study. Leukemia 1993; 7: 2064–2068. alterations of c-MYC and BCL6 have been established. 9 Bastard C, Tilly H, Lenormand B, Bigorgne C, Boulet D, Kunlin In summary, we stress the need for a thorough morphologic, A, Monconduit M, Piguet H. Translocations involving band 3q27 immunophenotypic, and cytogenetic assessment of all pedi- and Ig gene regions in non-Hodgkin’s lymphoma. Blood 1992; 79: atric malignancies. When possible, molecular genetic studies 2527–2531. should also be performed. These studies may improve both 10 Offit K, Jhanwar S, Ebrahim SA, Filippa D, Clarkson BD, Chaganti diagnostic accuracy and treatment selection.16,17 RS. t(3;22)(q27;q11): a novel translocation associated with diffuse non-Hodgkin’s lymphoma. Blood 1989; 74: 1876–1879. 11 Ye BH, Lista F, Lo Coco F, Knowles DM, Offit K, Chaganti RS, Dalla-Favera R. Alterations of a zinc finger-encoding gene, BCL- 6, in diffuse large-cell lymphoma. Science 1993; 262: 747–750. 12 Kerckaert JP, Deweindt C, Tilly H, Quief S, Lecocq G, Bastard C. Acknowledgements LAZ3, a novel zinc-finger encoding gene, is disrupted by recurring chromosome 3q27 translocations in human lymphomas. Nat Genet 1993; 5: 66–70. This work was supported in part by NIH Cancer Center Sup- 13 Lo Coco F, Ye BH, Lista F, Corradini P, Offit K, Knowles DM, port (CORE) grant CA-21765, Leukemia Program Project Chaganti RS, Dalla-Favera R. Rearrangements of the BCL6 gene Grant CA-20180, and by the American Lebanese Syrian Asso- in diffuse large cell non-Hodgkin’s lymphoma. Blood 1994; 83: ciated Charities (ALSAC). JER is supported in part by a Career 1757–1759. Development Award from the American Society of Clinical 14 Ye BH, Lo Coco F, Chang CC, Zhang J, Migliazza A, Cechova K, Knowles DM, Offit K, Chaganti RS, Dalla-Favera R. Alterations of Oncology. the BCL-6 gene in diffuse large-cell lymphoma. Curr Top Microbiol Immunol 1995; 194: 101–108.

1,2 1 15 Nakamura Y, Miki T, Kawamata N, Ohashi K, Hirosawa S, Koba- JE Rubnitz Departments of Hematology/Oncology, yashi H, Maseki N, Kaneko Y, Saito K, Enokihara H, Furusawa S. 13 B Abushullaih Diagnostic Imaging, and Two Burkitt-type lymphoma/leukemia-derived cell lines SC Kaste34Pathology and Laboratory Medicine, presenting 3q27 translocations and immunoglobulin/BCL6 chim- SC Raimondi4,5 St Jude Children’s Research Hospital, eric transcripts. Leukemia 1997; 11: 1993–1994. JT Sandlund1,2 and the Departments of 16 Rubnitz JE, Pui CıH. Recent advances in the biology and treatment C-H Pui1,2,4 2Pediatrics and 5Pathology, of childhood acute lymphoblastic leukemia. Curr Opin Hematol 4,5 1997; 4: 233–241. FG Behm University of Tennessee College 17 Rubnitz JE, Crist WM. Molecular genetics of childhood cancer: of Medicine, implications for pathogenesis, diagnosis, and treatment. Pediatrics Memphis, TN, USA 1997; 100: 101–108.