Case Report

Extramedullary B Lymphoblastic Leukemia/Lymphoma (B-ALL/B-LBL):

A Diagnostic ChallengePraveen Ramakrishnan Geethakumari,1 Marc S. Hoffmann,2 Naveen Pemmaraju,2

Shimin Hu,3 Jeffrey L. Jorgensen,3 Susan O’Brien,2 Naval Daver2

Clinical Practice Points

� Aggressive precursor B-cell neoplasms compriseB-cell acute lymphoblastic leukemia (B-ALL) andB-cell lymphoblastic lymphoma (B-LBL).

� B-cell lymphoblastic lymphomas account for only10% to 20% of cases of these aggressiveB-neoplasms and by definition have fewer than25% bone marrow blasts. B-LBL and B-ALL shareimmunophenotypic properties and are traditionallyclassified together.

� Precursor B-LBL frequently involves lymph nodes andextranodal sites including the skin, soft tissue, andcortical bone. It rarely presents with an isolated

mediastinal mass, which is typically pathognomic ofT-cell lymphoblastic lymphoma.

� Extramedullary lymphoid neoplasms require compre-hensive pathologic review including flow cytometry,immunohistochemistry, cytogenetics, and molecularanalysis to ensure diagnostic accuracy.

� Herein we describe a unique presentation of isolatedextramedullary B-ALL/B-LBL with no bone marrowinvolvement. Furthermore, we will review pertinentalbeit limited published literature, which might guidediagnosis and management of this entity.

Clinical Lymphoma, Myeloma & Leukemia, Vol. -, No. -, --- ª 2014 Elsevier Inc. All rights reserved.Keywords: CXCR4/SDF-1 signaling, Extramedullary, Lymphoblastic lymphoma,

Multiplanar flow cytometry, Multi-agent chemotherapy

IntroductionB-cell acute lymphoblastic leukemia/lymphoma (B-ALL/B-LBL)

accounts for 2% of lymphoid neoplasms diagnosed in the UnitedStates. The incidence appears to be increasing in children andadults. B-cell acute lymphoproliferative disease manifests as pureleukemia (B-ALL) in 80% of cases, isolated extramedullary disease(B-LBL) in 10%, and mixed B-ALL/B-LBL in 10% of cases.Extramedullary presentations frequently have marrow involvementat diagnosis that might be morphologically evident or might requiredetection using high-resolution flow cytometry.1-3

1Department of Internal Medicine, Albert Einstein Medical Center, Philadelphia, PA2Department of Leukemia, M.D. Anderson Cancer Center, University of Texas,Houston, TX3Department of Hematopathology, M.D. Anderson Cancer Center, University ofTexas, Houston, TX

Submitted: Oct 10, 2013; Revised: Jan 17, 2014; Accepted: Jan 23, 2014

Address for correspondence: Naval Daver, MD, Department of Leukemia, Unit 428,1515 Holcombe Blvd, The University of Texas M.D. Anderson Cancer Center,Houston, TX 77030E-mail contact: NDaver@mdanderson.org

2152-2650/$ - see frontmatter ª 2014 Elsevier Inc. All rights reserved.http://dx.doi.org/10.1016/j.clml.2014.01.004

Sternberg et al first recognized the correlation between nodal andleukemic presentations of pre-B-cell neoplasms in 1905.4 Hedescribed a patient with mediastinal lymphoma that subsequentlyprogressed to acute leukemia. Nathwani and colleagues establishedthe current morphologic description of “lymphoblastic lymphoma(LBL)” presenting with extramedullary mass lesions comprised ofcells indistinguishable from acute lymphoblastic leukemia (ALL).5,6

Current 2008 World Health Organization criteria continue toclassify B-ALL and B-LBL as a spectrum disorder, with B-LBLdefined according to the presence of extramedullary lesions withfewer than 25% marrow blasts.7,8

Herein we describe a case of isolated extramedullary B-LBL andreview the pertinent literature regarding diagnosis and management.

Case ReportA 45-year-old Hispanic man with no significant medical history

underwent resection of a left postauricular mass at an outsideinstitution in October 2011 that was interpreted as “myeloid sar-coma.” A whole-body positron emission tomography (PET)/computed tomography (CT) scan in January 2012 revealedabnormal fluorodeoxyglucose (FDG) uptake in multiple bones

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including the cervical, thoracic, and lumbar spine, bilateral humerii,femora, tibiae, and fibulae. Bone marrow aspiration/biopsy inFebruary 2012 revealed no evidence of systemic myeloproliferative,lymphoproliferative, or metastatic disease and the patient was placedon observation. He returned in April 2012 with a dental abscess,which was drained, and pathology revealed diffuse intertrabecularinfiltration by a proliferative clone that was CD34-positive(CD34þ), BCL2 (B-cell lymphoma 2)-positive, CD2 (weak),CD43þ, and TdTþ (Terminal deoxynucleotidyl transferase) with aKi-67 proliferation rate of 80%. The pathologic diagnosis was“T-cell LBL.” In May 2012, he was referred to M.D. AndersonCancer Center.

At referral, he had no specific complaints and denied “B”symptoms. Physical exam was notable for absence of lymphade-nopathy or hepatosplenomegaly. Laboratory investigations showednormal hemogram, liver, and renal function tests. Lactate dehy-drogenase and beta-2 microglobulin were elevated at 902 IU/L(normal, 313-618 U/L) and 3.7 mg/L (normal, 0.7-1.8 mg/L),respectively. Bone marrow biopsy showed 40% cellularity, trilineagehematopoiesis, and diploid cytogenetics with no morphologic evi-dence of lymphoma/leukemia. No monoclonal T-cell receptor betaor gamma rearrangements were identified in polymerase chainreaction analysis. High-sensitivity multiplanar flow cytometryrevealed no evidence of aberrant B cells. A repeat PET/CT scanshowed heterogeneous increased FDG uptake in multiple axialbones, retrosternal tissue, and spleen.

Percutaneous CT image-guided surgical biopsy of the PET-avidretrosternal tissue revealed diffuse effacement by sheets of monot-onous small- to medium-sized mononuclear blasts with scantcytoplasm, fine chromatin, and small nucleoli. Flow cytometry

Figure 1 Morphology and Immunophenotype of B-LBL and Whole B(Magnification 31000). (C) and (D) Lymphoma Cells are Pand (F) Lymphoma Cells are Positive for TDT, CD19, CD34Heterogeneous Increased FDG Uptake in Multiple Long BoRemission After R-HyperCVAD Chemoimmunotherapy

Abbreviations: APC-A ¼ allophycocyanin; B-LBL ¼ B-cell lymphoblastic lymphoma; CT ¼ computed toperidinin chlorophyll protein-tandem dye; PET ¼ positron emission tomography; R-HyperCVAD ¼alternating with high-dose methotrexate and cytarabine; TDT ¼ Terminal Deoxynucleotidyl transfera

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demonstrated a population of blasts that comprised 80% of theaspirate and positive for CD10, CD19 (100%), CD22 (>90%),CD34, CD38 (bright), CD43, CD44, CD45 (dim), CD123 (dim),CD200 (variable), human leukocyte antigen-DR, and TdT. Blastcells were negative for cyto-CD3, CD5, CD11c, CD13, CD14,CD20 (<5%), CD23, CD33, CD56, CD64, CD117, FMC-7,myeloperoxidase and surface kappa and lambda light chains. Thisanalysis was consistent with B-LBL (Fig. 1).

In June 2012, R-HyperCVAD (rituximab, hyperfractionatedcyclophosphamide, vincristine, doxorubicin, and dexamethasonealternating with high-dose methotrexate and cytarabine) chemo-immunotherapy was initiated. Our patient received intrathecalprophylaxis per protocol. He attained a complete radiologicalremission according to PET/CT scans performed after 3 cycles ofR-HyperCVAD (Fig. 1). He completed the scheduled 8 cycles ofR-HyperCVAD and remained in radiological remission. He iscurrently on POMP (prednisone, methotrexate, vincristine, andmercaptopurine) maintenance therapy.

DiscussionPurely extramedullary ALL is rare. Interestingly, recent reports

of isolated extramedullary ALL seem to focus on extramedullarypresentations involving the B-cell phenotype, namely B-LBL.9-18

Evolution of B-LBL with sequential involvement of differentextramedullary sites including the skin, dental tissue, and bone isunique to our case and hitherto has been poorly described.Furthermore, our case highlights the diagnostic challenges posed byextramedullary presentations of lymphoid leukemias, more specif-ically the need for complete immunophenotyping in accuratediagnosis.

ody PET/CT Images. (A) and (B) Histology and Cytology of B-LBLositive for CD19 and Negative for CD3 (Magnification 3500). (E), and CD38 Using Flow Cytometry. (G) PET/CT Image Showingnes and Axial Skeleton. (H) PET/CT Image Showing Radiologic

mography; FDG ¼ fluorodeoxyglucose; FITC-A ¼ Fluorescein isothiocyanate; PerCP-Cy5-5-A ¼rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasonese.

Praveen Ramakrishnan Geethakumari et al

The natural history of B-LBL is poorly defined and the bulk ofknown data emanate from case reports and small series. Extra-medullary leukemias are usually T-cell in origin. B-LBL comprisesonly 10% to 15% of lymphoblastic leukemia/lymphomas andfrequently involves lymph nodes and extranodal sites including skin,bone, and soft tissue. Mediastinal masses that characterize T-LBLare much less common in B-LBL. B-LBL might involve miscella-neous sites including head and neck (parotid gland, Waldeyer ring),retroperitoneum, mediastinum, pleura, breast, ovary, gastrointes-tinal tract, kidneys, brain, and soft tissue. B-LBL demonstrates ahigher incidence of skin involvement (33%) compared with ALL(1%).13,14,16,19,20

In immunohistochemistry, LBL blasts show positive periodic acidSchiff staining, variable positivity for nonspecific esterase, andSudan Black B, and negativity for myeloperoxidase. In B-LBL,tumor cells are positive for B-cell markers like CD19, CD79a, andCD22, frequently express CD10 (common acute lymphocytic leu-kemia antigen), CD24, paired box protein-5, TdT, and variablyexpress CD20, CD34, CD45, and CD99. The following antigen setis used to define stages of differentiation: ‘pro-B’ stage (CD10�,CD19þ, CD79aþ, CD22þ, nuclear TdTþ), ‘common’ stage(CD10þ), and ‘late pre-B’ stage (CD20þ, cytoplasmic heavy chain-positive). Coexpression of myeloid antigens, mostly CD13 andCD33 can occur in up to 30% of the cases. Some studies haveshown that LBL demonstrates a more “mature immunophenotype(mostly pre-B)” compared with ALL (Table 1).1,5,6,10,12,14,15,21

The differential diagnosis of extramedullary LBL includesaggressive mature B-cell lymphomas (blastoid mantle cell lym-phoma, Burkitt lymphoma, double-hit, and other gray zone lym-phomas), Ewing family tumors, and myeloid leukemias. T-ALL/LBL is morphologically indistinguishable from B-ALL/LBL, but canoften be distinguished by its expression of T-cell markers includingCD1a, CD2, CD3, CD4, CD5, CD7, and CD8. Most cases ofB-LBL express TdT and lack myeloperoxidase differentiating them

Table 1 Comparison of Clinical Manifestations, Immunophenotype,

Parameter B-LBL

Frequency 10% of LBL

Patients Aged Younger Than 18 Years 64%

Definition (WHO) Presence of mass lesions and <25%

Skin in Involvement 33%

Mediastinal Involvement 4%

CNS Disease 5%

Immunophenotype Mature “pre-B” common

TdTD 92%

CD10D 89%

Cytogenetic Abnormalities Additional chromosome 21q materialtrisomy, tetrasomy, additional 21qIg heavy chain rearrangement

Prognostic Indices No validated prognostic model for adPoor prognostic markers:(1) higher IPI(2) advanced stage

Abbreviations: ALL ¼ acute lymphoblastic leukemia; B-ALL ¼ B-cell acute lymphoblastic leukemia; BIPI ¼ International Prognostic Index; LBL ¼ lymphoblastic lymphoma; MRD ¼ minimal residual dise

from acute myeloid leukemia and granulocytic sarcoma. Theexpression of TdT and lack of surface immunoglobulin helpsdifferentiate B-LBL from more mature B-cell neoplasms. Thenegativity of cyclin D1 and CD5 with TdT expression differentiatesit from mantle cell lymphoma. Expression of TdT, CD34, CD43,and CD79a help differentiate B-LBL from Ewing family tumorsthat also express CD99.1,7

The pathophysiology of extramedullary involvement in ALL isnot fully discerned but might in part depend on CXCR4 (C-X-Cchemokine receptor type 4)/stromal derived factor-1 (SDF-1)signaling. Signaling involving chemokine receptor CXCR4 and itsligand, SDF-1/CXCL12 (C-X-C motif chemokine 12) mightmediate chemotaxis and transendothelial migration of pre-B cells toextramedullary tissues.22 CXCR4 overexpression has been demon-strated in lymphoblasts from patients with extramedullaryinvolvement and SDF-1 expression is not restricted to the bonemarrow microenvironment but has also been identified in the brain,lymph nodes, liver, and spleen. Similarly, CXCR4 antagonistsmobilize leukemic blasts to the peripheral blood and inhibit“extramedullary homing.”23 Another molecule of interest is thevascular endothelial growth factor receptor-1 (VEGFR-1 or FLT-1),which regulates the localization of ALL cells to the bone marrowand their survival and exodus to systemic circulation. FLT-1neutralization impedes the mobilization of leukemic cells and re-sults in apoptosis.24

Karyotyping shows differences in cytogenetic profiles betweenB-LBL and B-ALL (Table 1). For example, additional chromosome21q material including trisomy, tetrasomy, intrachromosomalamplification of AML1 gene (21q22) have been reported in B-LBLbut the cytogenetic aberrations typically associated with medullaryALL including hyperdiploidy, t(12;21), t(1;19), t(9;22), and t(4;11)are less frequent. Most of B-LBLs have clonal rearrangements of theimmunoglobulin heavy chain, with occasional rearrangement of thelight chain genes.1,13,14

and Cytogenetic Features of B-LBL and B-ALL5,6,10,12,14,15

B-ALL

85% of ALL

75%

marrow blasts >25% Bone marrow involvement

1%

1%

1%-3%

Immature phenotype

>90%

80%-90%

in form of22, clonal

Hyperdiploidy, characteristic translocations seen inALL including (12;21), t(1;19), t(9;22), and t(4;11)(rare in B-LBL)

ult LBL. Poor prognostic markers:(1) age > 35 years(2) leucocytosis > 30 � 109/L(3) karyotype: t(9;22), t(4;11), complex or hypodiploid(4) therapy-related: time to morphologic CR >4 weeks, persistent MRD

-LBL ¼ B-cell lymphoblastic lymphoma; CNS ¼ central nervous system; Ig ¼ immunoglobulin;ase; TdT ¼ Terminal deoxynucleotidyl transferase; WHO ¼ World Health Organization.

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Lymphoblastic lymphoma is highly aggressive with an inferiorprognosis to ALL. Three-year disease-free survival rates are 73% to90% for children and 45% to 72% for adults.1,25-28 A number ofprognostic factors affect the outcome of LBL. For example, B-LBLhas a better prognosis than T-LBL.1,7 A pediatric series identifiedadvanced stage as a significant adverse prognostic factor.21 A higherInternational Prognostic Index for non-Hodgkin lymphoma wasassociated with poor survival in adult LBL but not childhoodLBL.25 Central nervous system (CNS) involvement at diagnosis wasassociated with poor outcome in both B- and T-LBL, reported byThomas et al.28

Multiagent chemotherapy regimens traditionally used in B-ALLremain the standard therapy for B-LBL. The addition of rituximabto the modified HyperCVAD (hyperfractionated cyclophospha-mide, vincristine, doxorubicin, and dexamethasone alternating withhigh-dose methotrexate and cytarabine) regimen as front-line ther-apy has improved 3-year overall survival from 35% to 68%compared with HyperCVAD alone for adolescents and young adultswith B-ALL/LBL. Intensive intrathecal chemotherapy prophylaxis iseffective in preventing CNS relapses and might obviate the need forcranial irradiation. Mediastinal irradiation for patients with largemediastinal masses at diagnosis might reduce mediastinal relapses,especially in T-LBLs. Patients with adverse prognostic features atdiagnosis should be considered for autologous or allogeneic stem celltransplantation (SCT). Monitoring for minimal residual disease inLBL patients in first complete remission in bone marrow analysisand PET/CT imaging might help to identify subsets of patients whowill benefit from SCT in the future.20,21,25-28

ConclusionB-cell lymphoblastic leukemia/lymphoma can present with varied

extramedullary manifestations without bone marrow involvement asdemonstrated in our case. Identification and treatment of suchdiagnostically challenging cases requires interdisciplinary effort,incorporating leukemia specialists, radiologists, and pathologists.Unraveling the biology of extramedullary disease might reveal noveltherapeutic targets that could be exploited in the future.

DisclosureThe authors have stated that they have no conflicts of interest.

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