Hematopathology / CD23 EXPRESSION IN MANTLE CELL LYMPHOMA
`
`CD23 Expression in Mantle Cell Lymphoma:
`Clinicopathologic Features of 18 Cases
`
`Ellen Schlette, MD, Kai Fu, MD, PhD,* and L. Jeffrey Medeiros, MD
`
`Key Words: Mantle cell lymphoma; Chronic lymphocytic leukemia; CD23; Immunophenotype
`
`DOI: 10.1309/XV4AG7EMWQU7ER67
`
`A b s t r a c t
`The distinction between small lymphocytic
`lymphoma/chronic lymphocytic leukemia (SLL/CLL)
`and mantle cell lymphoma (MCL) has important
`clinical implications. Typically, SLL/CLL is CD23+,
`whereas MCL is CD23–. However, CD23 is expressed
`in a subset of MCLs, and the clinicopathologic features
`of patients with these neoplasms are not well described.
`We report 18 CD23+ MCLs, detected by flow cytometry
`in all cases (dim intensity, 16; bright intensity, 2), 5
`(28%), also positive by immunohistochemical analysis.
`There were 13 men and 5 women (median age, 56
`years), 5 of whom died (median survival, 46 months).
`Seventeen (94%) had bone marrow involvement.
`Lymphadenopathy (14 cases [78%]), splenomegaly (11
`cases [61%]), and leukemic involvement (10 cases
`[56%]) were common. Five cases (28%) had blastoid
`morphologic features. The frequency of CD23
`expression by MCL is method-dependent, being
`typically dim and most commonly detected by flow
`cytometry. In this small study group, bone marrow and
`leukemic involvement were relatively common.
`
`The classification of small B-cell lymphoproliferative
`disorders is based on a combination of clinical, morphologic,
`immunophenotypic and cytogenetic parameters, as is
`described in the World Health Organization classification.1
`Immunophenotyping by flow cytometric or immunohisto-
`chemical analysis is particularly helpful in establishing the
`diagnosis because there is significant clinical and morphologic
`overlap between these diseases and immunophenotyping
`results are readily available. By contrast, conventional cytoge-
`netics and fluorescence in situ hybridization (FISH) analysis
`for the t(11;14)(q13;q32), characteristic of MCL, require more
`time and may not be readily available to all practitioners.
`CD23 is a low-affinity IgE Fc receptor and a marker of
`activated B cells. It is expressed weakly or is absent in resting
`mature peripheral blood and lymphoid tissue B cells.2
`Among CD5+ B-cell lymphoproliferative disorders, expres-
`sion of the CD23 antigen is useful for distinguishing small
`lymphocytic lymphoma/chronic lymphocytic leukemia
`(SLL/CLL) from mantle cell lymphoma (MCL). The
`majority of SLL/CLL cases are CD23+, whereas MCL cases
`usually are CD23–. However, CD23 positivity can be
`observed in a subset of MCLs, and this finding can lead to
`diagnostic confusion.
`The frequency of CD23 positivity in MCL is uncertain. In
`many reports, CD23 has been negative in MCL.3-6 In reports
`that include CD23+ MCL cases, detected by flow cytometric
`or immunohistochemical analysis, the frequency of CD23
`expression has ranged from 2% to 45%.7-14 In these studies,
`CD23 positivity in MCL is discussed as a diagnostic pitfall,
`without description of the clinicopathologic features of these
`cases. Thus, potential differences between CD23– and CD23+
`MCL cases are unknown. We describe the clinicopathologic
`
`760 Am J Clin Pathol 2003;120:760-766
`760 DOI: 10.1309/XV4AG7EMWQU7ER67
`
`© American Society for Clinical Pathology
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`Pharmacyclics LLC - Ex. 2011
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`

`and immunophenotypic features of 18 cases of CD23+ MCL.
`In this group, CD23 expression was assessed by both flow
`cytometric and immunohistochemical analysis.
`
`Materials and Methods
`
`Case Selection
`Data for 18 patients with MCL, evaluated at The M.D.
`Anderson Cancer Center, Houston, TX, from March 1996 to
`June 2003, were included in this study. The diagnosis of
`MCL was supported by a combination of morphologic and
`immunophenotypic features with cytogenetic data in a subset
`of cases. All MCL cases were CD23+ shown by immunophe-
`notypic methods performed on bone marrow (BM), periph-
`eral blood (PB), or lymph node (LN) specimens. Clinical
`information, including sex and age, physical findings, treat-
`ment history, and follow-up, were available for all cases.
`
`Morphologic Evaluation
`Available diagnostic material included LN, spleen, BM,
`and PB specimens that were retrieved from the files of our
`department. BM samples were available for all 18 patients,
`and other tissue specimens were available for 15 patients. In
`1 case, the diagnosis of MCL was based on BM and PB
`specimens. The pattern of LN and BM involvement and
`cytologic features were assessed.
`
`Immunophenotypic Studies
`Flow cytometric immunophenotypic studies were
`performed at the time of initial evaluation at our institution
`on BM and PB specimens (7 cases), BM specimens (8
`cases), an LN specimen (1 case), a PB specimen (1 case), or
`on all 3 specimen types (1 case). The samples were assessed
`using 3-color flow cytometric analysis and a FACScan
`(Becton Dickinson, San Jose, CA) instrument. Lymphocytes
`were gated for analysis using CD45 expression and right-
`angle light scatter as described previously.3 Fluorescein
`isothiocyanate– and phycoerythrin-conjugated IgG1 and
`IgG2 antibodies were used as negative controls, and cursors
`were set to include more than 95% of events as negative. The
`panel of antibodies, conjugated to fluorescein isothiocyanate,
`phycoerythrin, or allophycocyanin, included reagents
`specific for CD3, CD5, CD19, CD20, CD23, FMC7, and
`immunoglobulin κ and λ light chains (Becton Dickinson).
`Immunohistochemical stains for cyclin D1 (AM29, Zymed
`Laboratories, South San Francisco, CA) and CD23 (1B12,
`Novocastra Laboratories, Newcastle upon Tyne, England) were
`performed using formalin-fixed, paraffin-embedded tissue
`sections of LN (n = 3) and BM, the latter either aspirate clot (n =
`12) or core biopsy (n = 3) specimens, as described previously.11
`
`Hematopathology / ORIGINAL ARTICLE
`
`Briefly, after deparaffinization and rehydration in graded alco-
`hols and xylene, endogenous peroxidase was blocked with
`hydrogen peroxide. Heat-induced epitope retrieval was
`performed by heating slides in EDTA buffer at pH 8.0, using a
`Black and Decker (Towson, MD) Handy Steamer Plus, and then
`cooling for 20 minutes. Immunostaining was completed using
`the LSAB2 detection kit (DAKO, Carpinteria, CA), with appro-
`priate positive and negative controls.
`
`Cytogenetic Studies
`Fourteen tumors were analyzed using conventional kary-
`otypic analysis. Cells were placed in 10 mL of Ham F10
`medium, with 20% fetal calf serum at a concentration of 2 ×
`106 to 4 × 106 nucleated cells per milliliter. The culture was
`incubated at 37°C for approximately 24 hours. Standard
`harvesting procedures were used. Colcemid (0.1 mL/10 mL)
`was added to the culture for 30 minutes at room temperature.
`For hypotonic treatment, a 0.075-mol/L concentration of
`potassium chloride was used for 30 minutes at room tempera-
`ture. The fixation procedure consisted of 3 changes of
`methanol/glacial acetic acid (3:1), with a 10-minute interval
`between each change. A drying chamber (Thermotron Indus-
`tries, Holland, MI) was used for slide preparation. Slides were
`placed in a 60°C oven overnight, followed by GTG banding.
`The karyotype reports were written using the International
`System for Human Cytogenetic Nomenclature (1995).15
`
`FISH Studies
`The commercially available LSI IGH/CCND1 dual-
`color, dual-fusion translocation probe (Vysis, Downers
`Grove, IL) was used, and FISH was performed using 5-µm-
`thick tissue sections of formalin-fixed, paraffin-embedded
`BM biopsy specimens.
`Briefly, tissue sections were mounted on positively
`charged slides, air dried, and baked overnight at 60°C. Slides
`then were deparaffinized in Hemo-De (Fisher Scientific,
`Pittsburgh, PA) (3 cycles, at ambient temperature), dehy-
`drated in 100% ethanol (room temperature), and air dried by
`placing the slides on a 45°C to 50°C slide warmer for 2 to 5
`minutes. The slides then were immersed in 0.2N hydrogen
`chloride for 20 minutes, followed by washes (3 minutes
`each) in purified water and wash buffer (2× standard saline
`citrate [SSC], pH 7.0). Pretreatment consisted of immersing
`in sodium thiocyanate solution (Vysis) at 80°C for 30
`minutes, again followed by washes in purified water and
`wash buffer. The tissue sections were digested in protease
`solution at 37°C for 10 minutes, washed in buffer, and dried
`on a slide warmer for 2 to 5 minutes. The slides were fixed in
`10% formalin/phosphate-buffered saline for 10 minutes (at
`ambient temperature) and washed in buffer solution. Denatu-
`ration of the probe mixture and specimen were performed at
`80°C (5 minutes) using the Vysis HYBrite hybridization
`
`© American Society for Clinical Pathology
`
`Am J Clin Pathol 2003;120:760-766 761
`761 DOI: 10.1309/XV4AG7EMWQU7ER67 761
`
`Exhibit 2011 Page 002
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`

`Schlette et al / CD23 EXPRESSION IN MANTLE CELL LYMPHOMA
`
`system. The probe mixture included 7 mL of LSI hybridiza-
`tion buffer, 1 mL of probe, and 2 mL of purified water. After
`an overnight hybridization at 37°C, the slides were washed
`in 2× SSC/0.1% NP-40 (Vysis) at 73°C for 2 minutes, rinsed
`in 2× SSC/0.1% NP-40 for 5 to 10 seconds at room tempera-
`ture, air dried in darkness, and counterstained with 10 mL of
`4,6-diamidino-2-phenylindole in antifade (DAPI).
`Hybridization signals were analyzed using a Zeiss Axioskop
`(Carl Zeiss Surgical, Thornwood, NY) equipped with appro-
`priate filters. Images were captured using the Cyto Vision
`imaging system (Applied Imaging, Santa Clara, CA).
`
`Results
`
`Clinical Features
`There were 13 men and 5 women with a median age of
`56 years at the time of initial diagnosis (range, 44-72 years).
`The referral diagnoses included MCL (12 cases), B-cell
`SLL/CLL (3 cases), B-cell prolymphocytic leukemia (1
`case), follicular small cleaved cell lymphoma (1 case), and
`diffuse large B-cell lymphoma vs MCL (1 case).
`At diagnosis, 6 patients had diffuse or localized
`lymphadenopathy, 7 patients were found incidentally to have
`lymphocytosis during routine examination, 1 patient had
`lymphadenopathy and lymphocytosis, 1 patient had
`lymphadenopathy and splenomegaly, 1 patient had
`splenomegaly, 1 patient had a colon mass, and 1 patient
`underwent bone marrow aspiration and biopsy for assessment
`of thrombocytopenia. Nine (50%) of 18 patients received
`chemotherapy before referral to our hospital.
`At our institution, 17 patients had lymphadenopathy (n =
`6), splenomegaly (n = 3), or both (n = 8). One patient did not
`have lymphadenopathy or splenomegaly but recently had
`received treatment. One patient had undergone splenectomy
`before coming to our institution. Of the 14 patients who had
`lymphadenopathy, multiple sites usually were involved. Of the
`11 patients with splenomegaly, the spleen size was reported as
`“palpable” or up to 22 cm inferior to the left costal margin.
`Serum levels of β
`2-microglobulin and lactate dehydro-
`genase were known for all 18 patients. The median β
`2-
`microglobulin level was 3.3 µg/mL (281 nmol/L; reference
`range, 0.6-2.0 µg/mL [51-170 nmol/L]) with a range from
`1.6 to 8.4 µg/mL (136-714 nmol/L); 16 patients (89%) had
`elevated levels. The median lactate dehydrogenase level was
`458 U/L (reference range, 313-618 U/L) with a range from
`75 to 1,319 U/L; 4 patients (22%) had elevated levels.
`
`Peripheral Blood Findings
`Ten (56%) of 18 cases had leukemic involvement,
`defined as a lymphocyte count of more than 5,000/µL (>5.0 ×
`
`109/L). In these 10 cases, the median WBC count was
`60,300/µL (60.3 × 109/L; range, 16,500-196,000/µL [16.5-
`196.0 × 109/L]) with a median absolute lymphocyte count of
`55,900/µL (55.9 × 109/L; range, 13,900-158,800/µL [13.9-
`158.8 × 109/L]).
`In the remaining 8 patients, the median WBC count was
`7,000 (7.0 × 109/L; range, 4,700-9,000/µL [4.7-9.0 × 109/L])
`with a median absolute lymphocyte count of 1,800/µL (1.8 ×
`109/L; range, 180-4,300/µL [0.18-4.3 × 109/L]).
`In 10 cases, peripheral blood smears were available for
`review, 7 from the leukemic group and 3 from the
`nonleukemic group. All 10 cases showed atypical lymphoid
`cells, morphologically consistent with MCL.
`
`Morphologic Features
`For 15 patients, LN, spleen, or extranodal specimens
`were available for review, including 13 LN, 3 spleen, 1 gall-
`bladder, and 2 endoscopic colon biopsy specimens. Of the
`13 LN specimens, 9 were obtained at the time of initial
`diagnosis and 4 were obtained 2 to 24 months after initial
`diagnosis.
`The pattern of LN involvement included mantle zone
`and nodular (1 case), nodular (3 cases), nodular and diffuse
`(3 cases), and diffuse (6 cases). In 10 cases, the MCL had
`typical small cell features ❚Image 1❚; 2 other cases were blas-
`toid (1 classic and 1 pleomorphic variant). In addition, 1 LN
`with a diffuse pattern and small cell cytologic features had
`focal clusters of large cells, suggestive of focal blastoid
`MCL, pleomorphic variant.
`Of 18 patients, 17 (94%) had BM involvement by MCL,
`representing 20% to 90% of the cellular elements. The
`patterns of involvement included nodular, interstitial, and
`diffuse and usually were found in multiple combinations.
`Fourteen cases had cytologic features of typical MCL on the
`BM aspirate smears. The neoplastic cells were predomi-
`nantly small to intermediate size and had irregular nuclear
`contours, inconspicuous nucleoli, and scant cytoplasm.
`Three cases showed classic blastoid morphologic features in
`the BM specimens. The neoplastic cells were of intermediate
`size with fine chromatin, inconspicuous nucleoli, and scant
`cytoplasm. One BM case showed prolymphocytoid morpho-
`logic features on the aspirate smears as the cells were of
`intermediate size with prominent nucleoli.
`Morphologic discordance between multiple biopsy sites
`was observed in 4 cases. Two cases that showed classic blas-
`toid morphologic features in tissue specimens had BM
`involved by typical MCL. In a third case, an LN specimen
`showed typical morphologic features, but in the BM spec-
`imen, the tumor was prolymphocytoid. In the fourth case, the
`initial BM specimen showed typical MCL. However, 30
`months later, the spleen and BM specimens showed blastoid
`MCL, pleomorphic variant.
`
`762 Am J Clin Pathol 2003;120:760-766
`762 DOI: 10.1309/XV4AG7EMWQU7ER67
`
`© American Society for Clinical Pathology
`
`Exhibit 2011 Page 003
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`

`

`A
`
`B
`
`Hematopathology / ORIGINAL ARTICLE
`
`❚Image 1❚ CD23+ mantle cell lymphoma; cyclin D1+. A, Histo-
`logic sections of lymph node show that the neoplastic cells are
`small, with irregular nuclei and minimal cytoplasm (H&E, ×400).
`B, Approximately 50% of the neoplastic cells are CD23+, with
`variable intensity of staining (immunoperoxidase with hema-
`toxylin counterstain, ×400). Flow cytometric analysis demon-
`strating expression of CD5 and CD19 (C) and expression of
`CD23 and dim FMC7 (D). FITC, fluorescein isothiocyanate; PE,
`phycoerythrin.
`
`clonal results in 9 cases. All 9 tumors showed the
`t(11;14)(q13;q32) with multiple additional karyotypic abnor-
`malities ❚Table 1❚. The 9 clonal cases included studies
`performed on BM (6 cases), LN (2 cases), and spleen and
`BM specimens (1 case).
`
`B
`
`104
`
`103
`
`102
`
`101
`
`CD23 PE
`
`A
`
`104
`
`103
`
`102
`
`101
`
`CD5 PE
`
`100
`100 101
`102
`103
`CD19 FITC
`
`104
`
`100
`100 101
`102
`103
`FMC7 FITC
`
`104
`
`❚Image 2❚ CD23+ mantle cell lymphoma; cyclin D1–. Flow cyto-
`metric analysis demonstrating expression of CD5 and CD19 (A)
`and CD23 and FMC7 (B). This case had 1 metaphase with the
`t(11;14) detected by conventional cytogenetics. Fluorescence in
`situ hybridization analysis showed 54% of nuclei with the
`t(11;14). FITC, fluorescein isothiocyanate; PE, phycoerythrin.
`
`D
`
`104
`
`103
`
`102
`
`101
`
`CD23 PE
`
`C
`
`104
`
`103
`
`102
`
`101
`
`CD5 PE
`
`100
`100 101
`102
`103
`CD19 FITC
`
`104
`
`100
`100 101
`102
`103
`FMC7 FITC
`
`104
`
`Immunophenotypic Results
`Flow cytometric immunophenotypic studies were
`performed in all cases and identified a CD5+ B-cell population
`with immunoglobulin light chain restriction (κ, 12 cases; λ, 6
`cases). All cases were positive for CD19, CD20 (bright, 13
`cases; dim, 2 cases; intensity not reported for 3 cases), and CD23
`and were negative for CD3 and CD10 (Image 1) ❚Image 2❚. Of
`18 cases, 14 (78%) were FMC7+. CD23 expression was defined
`as bright (>log102 mean fluorescence intensity) in 2 cases and
`dim (<log102 mean fluorescence intensity) in 16 cases. In the 7
`cases with flow cytometric results for both BM and PB speci-
`mens, no discordant results in antigen expression were identified.
`With immunohistochemical methods, cyclin D1 was
`expressed in 17 (94%) of 18 cases assessed. The 1 case that
`lacked cyclin D1 expression carried the t(11;14). CD23 was
`positive in 5 (28%) of 18 cases assessed. In 4 cases, CD23
`expression was weak and often detected focally, ranging from
`fewer than 5% to approximately 25% of neoplastic cells posi-
`tive. One case was strongly CD23+.
`
`Cytogenetic Results
`Fourteen cases were analyzed using conventional cyto-
`genetics, 3 of which also were analyzed by FISH, with
`
`© American Society for Clinical Pathology
`
`Am J Clin Pathol 2003;120:760-766 763
`763 DOI: 10.1309/XV4AG7EMWQU7ER67 763
`
`Exhibit 2011 Page 004
`
`

`

`Schlette et al / CD23 EXPRESSION IN MANTLE CELL LYMPHOMA
`
`In 2 cases (cases 10 and 11), a single, abnormal
`metaphase was detected. In 1 case, the abnormality was
`del(14q); this case was shown immunohistochemically to be
`cyclin D1+. The second case had 1 metaphase with the
`following karyotype: 45,XY,–8,t(11;14)(q13;q32),add(12)
`(p11.2), add(18)(q23). However, FISH studies confirmed the
`presence of the t(11;14) in 54% of nuclei examined. This
`case was immunohistochemically negative for cyclin D1.
`Three patients had a diploid karyotype. In these patients,
`the MCL was cyclin D1 positive and, in 1 case, FISH analysis
`confirmed the presence of a substantial number of nuclei with
`the t(11;14).
`
`Follow-up Information
`The median time of clinical follow-up was 52 months
`(range, 2-77 months). Eight patients were treated at our insti-
`tution with fractionated cyclophosphamide, vincristine, lipo-
`somal daunorubicin, and dexamethasone (Hyper CVXD) plus
`rituximab (anti-CD20). Eleven patients were treated in a
`nonuniform manner at other institutions. Five patients died.
`The median time from diagnosis until death was 46 months
`(range, 28-77 months).
`
`Discussion
`
`The frequency of CD23 expression in MCL, as reported
`in the literature, varies widely, ranging from 0% to 45% of
`cases. These results are summarized in ❚Table 2❚.6-8,10-14,16-27
`As shown in Table 2, the method of detection is important for
`assessing the frequency of CD23 positivity. By using
`immunohistochemical methods in 7 studies, 4 (3.6%) of 110
`MCL cases were positive for CD23.8,10,16-18,24,25,27 By
`contrast, using flow cytometry in 9 studies, 21 (14.4%) of 146
`
`MCL cases were CD23+, including in the study by Gong and
`colleagues,14 in which 45% of MCL cases had dim CD23
`expression.6,7,11,14,19,20,24,25,27 Thus, the increased sensitivity of
`flow cytometry is needed to detect CD23 in most MCL cases,
`suggesting that CD23 positivity typically is dim.
`In the present study, we compared flow cytometric
`analysis, which was performed as a part of the initial diag-
`nostic evaluation, with immunohistochemical analysis in all
`cases. Only 5 cases positive by flow cytometric analysis
`were also positive immunohistochemically. In 4 of 5 cases,
`immunohistochemical detection of CD23 was weak and
`often detected focally. Similar results were reported by
`Tworek and colleagues.24 Although the discrepancy between
`flow cytometric and immunohistochemical results also may
`be related to the type of fixative used before immunohisto-
`chemical analysis, as suggested by others,25 all tissue speci-
`mens in the present study were fixed in formalin.
`In addition to CD23 positivity, 4 (22%) of 18 cases in this
`study were FMC7–. FMC7 is another marker useful for distin-
`guishing SLL/CLL from MCL, as SLL/CLL cases usually are
`negative and MCL cases usually are positive.20 In fact, some
`have advocated using the combination of CD23 and FMC7 for
`differential diagnosis.14,24 Thus, the potential for misdiagnosis
`of these MCL cases as SLL/CLL exists if flow cytometric
`results are not correlated with other findings. In our study, 1 of
`the 4 CD23+, FMC7– cases with leukemic involvement was
`misdiagnosed initially as SLL/CLL. However, all 4 cases had
`the t(11;14)(q13;q32), and cytogenetic results helped establish
`the correct diagnosis in the 1 misclassified case.
`CD23, a 45,000-kd glycoprotein, is a low-affinity Fc receptor
`for IgE that is expressed by a subpopulation of normal resting B
`cells that express surface IgM and IgD.28 CD23 also is overex-
`pressed in SLL/CLL. However, whether CD23 has a role in the
`
`❚Table 1❚
`Summary of Abnormal Cytogenetic Findings
`
`Case No.
`
`Tissue
`
`Cytomorphologic
`Features
`
`Karyotype
`
`1
`2
`
`3
`4
`
`5
`
`6
`7
`8
`9
`10
`11
`
`BM
`BM
`
`Typical
`Blastoid
`
`BM; spleen
`LN
`
`Typical
`Blastoid
`
`BM
`
`BM
`BM
`LN
`BM
`BM
`BM
`
`Typical
`
`Typical
`Typical
`Typical
`Typical
`Blastoid
`Typical
`
`43-46,XY,+3,t(5;8)(q34;q13),add(6)(p22),add(7)(q36),–7,–9,t(11;14)(q13;q32),–17,–18,+20,–21,+mar[cp11]
`46,XY,+3,add(5)(p15),t(11;14)(q13;q32),–13[2]/46-48,XY,+3,add(5)(p15),–9,t(11;14)(q13;q32),
`–15,–17,–18,+19,+21,+1-6mar[cp15]
`46,XY,del(7)(q32),t(11;14)(q13;q32),add(16)(q24)[11]
`40-45,X,–Y,del(1)(p34.3p36.2),inv(1)(p22q21),–5,del(6)(q15q25),–8,t(11;14)(q13;q32),
`del(12)(q24.1q24.3),–18,add(22)(q13),+1-3mar[cp10]
`42-46,XX,add(1)(p36),add(3)(q29),–4,add(5)(p15),add(9)(p24),–11,add(11)(p15),+12,add(12)(q24),
`–13,–14,der(14)t(11;14)(q13;q32),–15,–17,–18,–20,–22,+3-8mar[cp18]
`42-46,XY,–2,der(10)t(2;10)(q21;q26),t(11;14)(q13;q32),+0-2mar[cp7]*
`46,XY,t(11;14)(q13;q32),add(22)(q13)[8]
`46,XX,t(11;14)(q13;q32),add(17)(p10)[17]
`46,XY,t(11;14)(q13;q32)[2]
`45,XY,–8,t(11;14)(q13;q32),add(12)(p11.2),add(18)(q23)[1]*
`46,XY,del14q[1]†
`
`BM, bone marrow; LN, lymph node.
`* Presence of t(11;14) confirmed by fluorescence in situ hybridization studies.
`† This case was positive for cyclin D1.
`
`764 Am J Clin Pathol 2003;120:760-766
`764 DOI: 10.1309/XV4AG7EMWQU7ER67
`
`© American Society for Clinical Pathology
`
`Exhibit 2011 Page 005
`
`

`

`pathogenesis of SLL/CLL or simply is a marker remains unclear.
`Nevertheless, in vitro studies have shown that cross-linking of
`CD23 molecules on SLL/CLL cells by anti-CD23 monoclonal
`antibody, or by its natural ligand (IgE), inhibits cytokine-
`induced DNA synthesis.29 These results suggest that signaling
`through the surface CD23 molecule has a negative effect on the
`growth and proliferation of SLL/CLL, potentially explaining the
`more indolent nature of this disease.30,31
`Whether CD23 expression in MCL confers a similar
`negative effect on the growth and proliferation of the
`neoplastic cells is not known. The 5 patients who died in this
`study had a median survival of 46 months. This survival is
`longer than that reported in the literature for patients with
`MCL, which is 36 months. In addition, 3 cases of leukemic
`MCL in the present study were detected incidentally and
`initially were thought, based on clinical grounds, to have
`SLL/CLL. Thus, patients with CD23+ MCL may have a
`more indolent disease course than typical MCL. However, as
`many of these patients were treated with newer chemothera-
`peutic regimens, such as Hyper CVXD and rituximab,
`therapy also may have led to their longer survival.
`Based on our findings, the cases of CD23+ MCL clinically
`resembled CD23– MCL cases reported in the literature in many
`ways. There was a male predominance (72%). Physical and
`laboratory findings included lymphadenopathy, splenomegaly,
`and elevated β
`2-microglobulin levels with normal LDH levels in
`most cases. However, differences in patient age and the
`frequency of BM and PB involvement in patients with CD23+
`MCL are noted. The median age of the 18 patients was 56 years
`in the present study, compared with 63 to 68 years in other
`studies of patients with MCL.7,11,32 BM involvement in this
`group (17/18 [94%]) also was higher than that reported for
`MCL cases in the literature. For example, MCL in the Non-
`Hodgkin’s Lymphoma Classification Project involved BM in
`64% of the cases.33 Similarly, most studies in the literature
`report leukemic involvement in 25% of MCL cases,1 which is
`lower than the 56% (10/18) frequency in the present study.
`The overall incidence of blastoid morphologic features in
`MCL has been reported in 17% to 38% of MCL cases,34-36
`which is similar to the 28% of blastoid cases in this small
`series. Any correlation between morphologic features and
`CD23 positivity in MCL has been investigated and reported
`only rarely. Dunphy and colleagues21 described 6 cases of blas-
`toid MCL that were all CD23–. In contrast, Kumar and
`colleagues8 suggested that CD23 positivity is more common in
`blastoid MCL. Our data suggest that CD23 positivity is present
`with similar frequency in small cell and blastoid MCL.
`In the present study, we had 1 BM case that had prolym-
`phocytoid morphologic features, which we do not consider
`synonymous with blastoid morphologic features. The rela-
`tionship between blastoid MCL and prolymphocytoid or
`nucleolated MCL is unclear, as the criteria for blastoid MCL
`
`Hematopathology / ORIGINAL ARTICLE
`
`❚Table 2❚
`Summary of CD23 Expression Reported in the Literature
`
`Method and Reference
`
`Immunohistochemical analysis
`Zukerberg et al18
`Dorfman and Pinkus16
`Zoldan et al10
`Kumar et al8
`Kurtin et al17
`Flow cytometry
`Cuneo et al6
`Kilo and Dorfman19
`Argatoff et al7
`Schlette et al11
`Garcia et al20
`Gong et al14
`Koiso et al27
`Both methods
`Dunphy et al21
`Bosch et al22
`Cohen et al23
`Wong et al13
`Tworek et al24
`Flow cytometry
`Immunohistochemical analysis
`de Leon et al25
`Flow cytometry
`Immunohistochemical analysis
`Method not stated
`Pittaluga et al26
`Samaha et al12
`
`CD23+ Mantle Cell
`Lymphoma Cases*
`
`0/13 (0)
`2/15 (13)
`1/14 (7)
`1/39 (3)
`0/11 (0)
`
`2/7 (29)
`0/10 (0)
`1/49 (2)
`3/23 (13)
`0/17 (0)
`10/22 (45)†
`2/7 (29)
`
`0/6 (0)
`5/37 (14)
`0/10 (0)
`2/14 (14)
`
`3/8 (38)
`0/8 (0)
`
`0/3 (0)
`0/10 (0)
`
`0/55 (0)
`3/55 (5)
`
`* Data are given as number positive/total number tested (percentage).
`† Reported as dim staining.
`
`are based on histologic sections, whereas the prolymphocy-
`toid variant of MCL has been described in BM aspirate or
`PB smears, making comparison between these morphologic
`types difficult.11,37,38 The prolymphocytoid variant of MCL
`can cause further diagnostic confusion if the neoplasm is
`CD23+, as such cases are more likely to be misdiagnosed as
`prolymphocytoid transformation of SLL/CLL or B-cell
`prolymphocytic leukemia.3,11
`
`From the Department of Hematopathology, The University of
`Texas M.D. Anderson Cancer Center, Houston.
`
`Address reprint requests to Dr Schlette: Dept of
`Hematopathology, The University of Texas M.D. Anderson Cancer
`Center, 1515 Holcombe Blvd, Unit 72, Houston, TX 77030.
`* Dr Fu is now with the Department of Pathology and
`Microbiology, University of Nebraska Medical Center, Omaha.
`Acknowledgments: We thank Kimberly Hayes for assistance
`with the conventional cytogenetics and FISH information and Andrea
`Sedo for assistance with preparing the manuscript and graphics.
`
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`765 DOI: 10.1309/XV4AG7EMWQU7ER67 765
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`
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