Case 5 -

Mantle Cell Lymphoma Paul E. Wakely, Jr.

Clinical History A 44 y/o woman presents with enlarged cervical, axillary and inguinal lymph nodes which she states appeared about four months ago. FNA biopsy was performed on an enlarged cervical lymph node. Cytopathology: Case 5 - Figure 1 - Case 5 - Figure 2 - hypercellular smears composition: monotonous small lymphocytes (slightly larger or similar in size to mature lymphocytes) in a single cell pattern LGBs present in large amounts in most areas of the smear most nuclei rounded, but some have slight irregularities of their nuclear border FC fragments, TBMs, and transformed lymphocytes absent Diagnosis: Mantle Cell Lymphoma Discussion Mantle cell lymphoma (MtCL), Clinical: biologically aggressive small cell B-cell lymphoma; about 6% of MLs occurs primarily in adults >50 years of age; rare in children affects men much more often than women (5:1) commonly extranodal as well as within lymph nodes most have disseminated disease(bone marrow) at the time of diagnosis much poorer prognosis than other small cell lymphomas with a median survival of only 2-5 years (Table 28) In the old NCI Working Formulation, most examples of MtCL were classified as diffuse small cleaved cell lymphoma. A t(11;14) translocation in almost three quarters of patients produces an up-regulation of the bcl-1(PRAD1) gene which in turn leads to overexpression of a protein termed cyclin D1. It has been shown that this translocation can be seen using FISH technology on aspirates. Tissue sections of this lymphoma (as may occur if cell blocks are obtained from the aspirate) show positive nuclear staining of this protein. Table 28. Prognosis of Malignant Lymphomas – Overall Survival(OAS) OAS, 5 yr. >70% OAS, 5 yr. 50-70%   Follicular lymphoma   Marginal zone, B-cell, nodal type   Marginal zone B-cell, MALT type   Small lymphocytic lymphoma   ALCL, T-/null cell   Lymphoplasmacytic lymphoma OAS, 5 yr. 30-49% OAS, 5 yr. <30%   Diffuse large B-cell lymphoma   Peripheral T-cell lymphoma   Mediastinal large B-cell lymphoma   Peripheral T or B lymphoblastic   Burkitt/Burkitt-like lymphoma   Mantle cell lymphoma Blood 1997;89:3909-18 Aspirates of MtCL: features overlap with other small cell lymphomas which are the principal considerations in the differential diagnosis nuclear irregularity/ grooves much less exaggerated than those seen in follicular lymphoma plasmacytoid lymphocytes, centroblasts, and paraimmunoblasts almost always absent constant monomorphism with a complete lack of lymphocyte heterogeneity readily removes RLH from consideration. Pitfall: An exception to the "rule" of lymphocyte monotony = lymphoma is that a minimally reactive lymph node can show little if any polymorphism, and thus imitate a small cell lymphoma. Clinical correlation is mandatory in every situation. In contrast to tissue, the diffuse, nodular, and mantle zone architectural patterns of MtCL cannot be appreciated in aspirates. A blastic variant of MtCL exists, and the cells resemble lymphoblasts. Immunophenotyping shows a B-cell lymphoma with a characteristic phenotype [CD5/CD43 positive; CD10/CD23 negative] which helps to differentiate it from small lymphocytic lymphoma (CD23 positive) and follicular lymphoma [CD10 positive, CD43 negative]. Differential Diagnosis of MtCL The other small B-cell lymphomas constitute the differential diagnosis of MtCL. In many instances cytomorphology alone is limited in its ability to discern among these various lymphoma subtypes. Yet, it is extremely important to do so because of the differences in immunology and biology of these tumors. There is wide variation in the therapy (sometimes no therapy is administered for some B-cell lymphomas), and prognosis. Small lymphocytic lymphoma (SLL), Clinical: comprises about 6% of non-Hodgkin lymphomas primarily a lymphoma of older adults with patients under 40 being rare a low grade indolent lymphoma, but not amenable to therapy (Table 12) disease often widespread at the time of diagnosis [splenomegaly, hepatomegaly, peripheral blood, and bone marrow involvement common] asymptomatic patients often receive no treatment The histopathology of SLL is most often a complete effacement of nodal architecture with interspersed pseudofollicular growth centers. These pseudofollicles contain prolymphocytes and paraimmunoblasts admixed with small lymphocytes. Aspirates of SLL: cellular uniformity with very high nuclear/cytoplasmic (N/C) ratios cells minimally larger than mature lymphocytes nuclei in tissue sections are typically described as having coarse clumped chromatin – so-called clotted chromatin (cellules grumelées). In smears this coarse "block" type of chromatin pattern (best seen in Papanicolaou stained smears) may be repeated, or nuclei may have a dense smudged appearance nuclear borders are smooth or minimally irregular in SLL because of the presence of pseudofollicular growth centers, occasional transformed lymphocytes[prolymphocytes and paraimmunoblasts] are seen prolymphocytes: large lymphocytes with distinct nucleolus, modest amount pale cytoplasm paraimmunoblasts: slightly larger than prolymphocytes with perhaps a slightly larger nucleolus and more basophilic cytoplasm These two types of transformed lymphocytes may not be distinguishable from each other in smears because of their overlapping features, nor is it necessarily critical to do so. Involvement of a lymph node by chronic lymphocytic leukemia is identical to that of SLL. TBMs and FC fragments are rare- absent. Immunoprofile of SLL: nearly identical to MtCL with the major exception of CD23 positive cells in the former (Table 13). Large cell transformation (Richter syndrome) is a complication of SLL in <10% of cases. Table 29. Clinical Features of Small Cell B-cell Lymphomas Type Age/Gender Stage I Extranodal Clinical Course SLL/CLL 60/ m>f none rare indolent, incurable LpL 60/ m>f none rare indolent, incurable Mantle cell 60/ m>>f rare many aggressive, incurable Follicular 50/ m=f rare rare indolent, rarely curable Marginal zone/MALT 50/ m often usually indolent, curable Lymphoplasmacytic lymphoma (LpL)occurs in the same age group as SLL, but at a much lower incidence (about 1% of cases). It is an indolent lymphoma of the elderly with diffuse lymphadenopathy, monoclonal serum paraproteinemia, and possibly symptoms of hyperviscosity (Waldenstrom's macroglobulinemia). Aspirates are characterized by a large percentage of plasmacytoid lymphocytes with well developed features of plasmacytic differentiation: a greater amount of cytoplasm/eccentrically placed nuclei. Globular immunoglobulin cytoplasmic inclusions (Russell bodies), and nuclear pseudoinclusions (Dutcher bodies) have been described. Plasmacytic immunoblasts and plasma cells may be seen. SLL and Follicular lymphoma with plasmacytoid features can be confused easily for LpL on smears. Immunophenotyping is required to separate. Table 30. Differential Immunophenotyping of Small & Intermediate Sized-Cell B-Cell Lymphomas CD# SLL LpL MtCL FL MZL LL Burkitt CD5 pos neg/pos pos neg neg pos/neg neg CD10 neg neg neg/pos pos/neg neg neg/pos pos CD20 pos/neg pos pos pos pos neg/pos pos CD23 pos neg neg neg neg neg neg FMC-7 neg ± pos pos pos     CD43 pos neg/pos pos neg neg/pos pos neg TdT neg neg neg neg neg pos neg SLL: small lymphocytic lymphoma LP: lymphoplasmacytic lymphoma MtCL: mantle cell lymphoma FL: follicular lymphoma MZL: marginal zone lymphoma LL: lymphoblastic lymphoma. Table 31. Controversy Regarding Malignant Lymphoma Diagnosis Using FNA   Customary Use of FNA in Lymphoma Cases Diagnose Recurrent Lymphoma Exclude a Diagnosis of Lymphoma If Primary Diagnosis of Lymphoma Suspected Þ Open Biopsy Application of FNA in lymph nodes relatively well accepted for: infectious conditions, RLH, and metastatic carcinomas. When applied to the diagnosis of malignant lymphoma(ML) - particularly a new diagnosis of ML - opinion on the efficacy of FNA is markedly divided. Entire spectrum of opinion with editorials both for or against the application of FNA in ML diagnosis exists in the literature. "At the Karolinska Hospital the majority of patients with lymphomas are not only diagnosed based on FNAC material but are also treated based on this diagnosis." Cancer (Cancer Cytopathol)2000;90:320-22. Possible reasons for this controversy include: most cytopathologists are not hematopathologists and vice-versa. difficult to apply the various previous lymphoma classifications to smears. wide spectrum in degree of diagnostic difficulty among the various lymphoma subtypes. expertise widely variable. issue of adequacy may be challenged(and thus legal implication regarding standard of care) if outcome does not conform to a preconceived result political "turf" issue between hematopathology and cytopathology(e.g. control of flow cytometry laboratory) loss of lymph node tissue for research needs Two major impediments to success in FNA lymphoma diagnosis include: a.) insufficient procurement of cells through sampling error/technique, and b.) the classification of ML itself. Acquisition of enough cells is paramount not only for morphologic analysis of the smear, but for ancillary studies. The principal adjunct test required of all FNAs presumptive of NHL is immunologic phenotyping. Accomplished either with: flow cytometry [which is probably the most popular and preferred technique because of the large number of antibodies that can be applied to the specimen if enough cells are present], cytospin slides, or preparation of a cell block with immunohistochemical staining identical to that performed on tissue sections Table 32. Immunophenotyping of Lymph Node FNA.   flow cytometry cytospins number of markers many fewer kappa/lambda ratio easily calculated subjective morphology lost preserved cells required many fewer detection of small monoclonal population good fair to poor multiple labeling easy laborious Hodgkin lymphoma useless useful Note: It has become clear that (with few exceptions) immunophenotyping is essential if accurate subtyping of non-Hodgkin lymphoma is expected from FNA biopsy. Table 33. Lymph Node FNA Immunophenotyping. Kaleem et al. [Mod Pathol 1999;12:46A] • 93 consecutive lymph node aspirates • FNA Diagnosis: Before Immunophenotyping definitive[benign/malignant] 18% atypical 66% non-committal 16% After Immunophenotyping definitive 88% atypical 12% • Tissue Dx: 34 benign, 46 NHL, 1 AML, 1 Hodgkin • 46% NHL subclassified The major classification used for ML in the past two decades in North America (Working Formulation) has been a major hindrance to subtyping ML using FNA because it was based to a large degree on evaluation of the tumor pattern within the node (follicular, diffuse, sinusoidal). Note: FNA cytopathology will not recognize a specific architectural pattern of lymphoma [follicular, diffuse, paracortical, sinusoidal, capsular/extranodal invasion, partial involvement] within a lymph node. The new WHO Classification of Lymphoid Neoplasms was published in 2001. Jaffe ES, Harris NL, Stein H, Vardiman JW(Eds.). World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Haematopoietic and Lymphoid Tissues. IARC Press: Lyon 2001 This classification should be greeted with enthusiasm by those practicing FNA. It markedly de-emphasizes the importance of architectural pattern/spatial relationships within the node; proposes that ML is multiple diseases, not a single disease; focuses primarily on the cell type [morphology, immunophenotype, genotype] in combination with the clinical features to classify each of these lymphomas. Table 34. Pathologic Diagnosis/WHO Classification of Lymphoma No one "gold" standard Incorporation of all available information   Morphology   Immunophenotype   Clinical features   Genetic features Table 35. WHO Classification of Tumors of Lymphoid Tissues, B-Cell Neoplasms Precursor B-cell neoplasm   Precursor B lymphoblastic leukemia/lymphoma. Mature B-cell neoplasms.   Chronic lymphocytic leukemia/small lymphocytic lymphoma   B-cell prolymphocytic leukemia   Lymphoplasmacytic lymphoma   Splenic marginal zone lymphoma   Mantle cell lymphoma   Follicular lymphoma   Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT-lymphoma)   Nodal marginal zone lymphoma   Hairy cell leukemia   Diffuse large B-cell lymphoma   Mediastinal(thymic) large B-cell lymphoma   Intravascular large B-cell lymphoma   Primary effusion lymphoma   Burkitt lymphoma / leukemia   Solitary plasmacytoma of bone   Extraosseous plasmacytoma   Plasma cell myeloma B-cell proliferations of uncertain malignant potential   Lymphomatoid granulomatosis   Post-transplant lymphoproliferative disorder, polymorphic Diagnoses in Bold are the more common forms of B-cell neoplasia. Accuracy of Lymphoma Diagnosis by FNA Oncologists expect that once a diagnosis of ML is made, it should be accurately classified. If one is to strongly advocate for FNA to replace this time tested method, then the FNA community will have to acquire the knowledge and use the tools for proper classification. Published accuracy of lymphoma diagnosis by FNA varied greatly in the past, in part because many authors did not use immunophenotyping to assist in subclassification. Some centers/pathologists use FNA as a screening test for lymphoma diagnosis. A "true" diagnosis of lymphoma with correct lymphoma subtype would have to wait until after the lymph node has been excised (which should be the next step in management). On the other hand, if one is to use FNA as a diagnostic test for lymphoma, as is done with a tissue specimen, then these diagnostic phrases [in table 36] are insufficient in the newly diagnosed patient. Table 36. Lymph Node FNA – Levels of Diagnostic Confidence Requires Open Biopsy   Atypical Lymphoid Cells   Malignant Lymphoma, NOS   Small Cell Malignant Lymphoma   Large Cell Malignant Lymphoma Does Not Require Open Biopsy   Specific Lymphoma Subtype, e.g. Mantle Cell Lymphoma Table 37 shows a wide spectrum in the ability to recognize ML and to correctly classify it. One must remember that those centers with mediocre results are less likely to publish them. Also, higher accuracy results are seen when FNA is performed for recurrent, not newly diagnosed ML. Table 37. FNA Diagnosis of NHL [Wakely P. Diagn Cytopathol 2000;22:120] 30 random articles: 1989-1999 total of 1,997 cases; case range per paper 4-324 sensitivity: 0-100% sensitivity: > 80% in 70% of articles specificity: > 90% in all but 2 articles subclassification: accurate in 79% of cases An update demonstrating the evidence of FNA in the diagnosis of lymphoma: Tables 38. FNA Dx of ML – 2000-2001 Reference # cases sensitivity (%) specificity (%) subclassification (%) Diag Cytopathol [2001;24:90] 56 85 100 82 Am J Clin Pathol [2000;114:18] 81 90 100 not done Am J Clin Pathol [2000;113:688] 206 82 85 73 Diag Cytopathol [2001;24:1] 127 88 100 77 Cancer [2001;93:51] 33 92 100 75 Mod Pathol [2001;14:472] 139 95 100 77 TOTAL 642 89 98 77 References for All Cases