Histological and immunoglobulin VH gene analysis of interfollicular small lymphocytic lymphoma provides evidence for two types

Chronic lymphocytic leukemia/small lymphocytic lymphoma: another neoplasm related to the B-cell follicle?

Although there has been increased attention paid to the critical nature of nodal involvement in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), the B-cell compartment it is most closely related to and its relationship to the follicle remain uncertain. A clinicopathologic investigation of 60 extramedullary biopsies of LEF1+ CLL/SLL, including 29 cases with perifollicular/follicular (PF/F) growth, was therefore performed. A subset of PF/F cases demonstrated inner mantle zone preservation or intra-mantle zone growth. All PF/F and 16/31 other cases contained CD21+ follicular dendritic cells. No cytogenetic, IGHV mutational or gene usage differences were seen between PF/F and diffuse cases. PF/F cases were more often kappa positive (p<0.03) and had fewer involved nodal sites (p=0.0004). These findings suggest that at least a subset of bona fide CLL/SLL is related to the follicle, most likely the outer mantle zone, and that at least a subset of the diffuse cases may represent "later" disease.

Richter syndrome with follicular colonization of chronic lymphocytic leukemia/small lymphocytic lymphoma cells mimicking follicular lymphoma

Follicular colonization is occasionally observed in marginal zone lymphoma. In rare cases, it has also been associated with mantle cell lymphoma. Chronic lymphocytic leukemia typically involves nodal or extranodal tissues as diffuse proliferation by complete effacement of the normal architecture. The involvement of chronic lymphocytic leukemia may be less frequently limited to the interfollicular areas. Here, we report a case of Richter syndrome of the small intestine that was initially diagnosed as follicular lymphoma of the gastrointestinal tract because of a partial follicular growth pattern in addition to a mainly diffuse proliferation pattern. The follicular pattern mimicking follicular lymphoma was shown to be composed of reactive follicles with follicular colonization of the original chronic lymphocytic leukemia cells. As the prognoses of Richter syndrome and follicular lymphoma of gastrointestinal tract are quite different, clinicians must carefully diagnose these conditions to avoid a misdiagnosis.

Chronic lymphocytic leukemia/small lymphocytic lymphoma with cyclin D1 positive proliferation centers do not have CCND1 translocations or gains and lack SOX11 expression

Cyclin D1 expression, usually absent in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), has been described in the proliferation centers (PC) of some CLL/SLL. The prevalence of this finding is uncertain, as is the explanation for its occurrence and whether these cases have any other unique features. Cyclin D1 immunohistochemical staining was therefore investigated in 57 extramedullary CLL/SLL biopsies. In 6 cases, cyclin D1 immunofluorescence followed by CCND1 fluorescence in situ hybridization (FISH) and PC targeted analysis was performed using a Bioview Duet system. Excluding the prospectively selected cases that had the targeted FISH studies, cyclin D1+ PC were identified in 20% of cases. The cyclin D1+ CLL did not appear pathologically or phenotypically distinctive, though 46% had an interfollicular growth pattern. The cyclin D1+ PCs were SOX11- and lacked CCND1 translocations and gains in 5 of 5 informative cases. The recognition of cyclin D1 expression in PC of a significant minority of CLL/SLL can be a diagnostic aid and should not lead to the diagnosis of focal mantle cell lymphoma.

Chronic lymphocytic leukemia: the pathologist's view of lymph node microenvironment

Chronic lymphocytic leukemia (CLL), an indolent B-cell malignancy frequently diagnosed in the elderly, is characterized by the relentless accumulation of CD5+ monoclonal B cells that proliferate in the appropriate tissue microenvironments. Despite many advances achieved by molecular and functional studies, our knowledge of the reciprocal relationship between the CLL cell and its microenvironment at the tissue level is still largely incomplete. In this review we present the relevant current information on the tissue microenvironmental features of CLL, focusing on the events that appear to occur in the lymph node. Special attention is devoted to analyzing the properties of both neoplastic and nonneoplastic bystander cells within proliferation centers, the mysterious structures that likely represent the actual proliferative compartment.

Reassessment of small lymphocytic lymphoma in the era of monoclonal B-cell lymphocytosis

BACKGROUND

In the 2008 World Health Organization classification, small lymphocytic lymphoma is defined as a neoplasm with the tissue morphology and immunophenotype of chronic lymphocytic leukemia, but with absence of leukemia. Minimal criteria of tissue involvement to separate small lymphocytic lymphoma from monoclonal B-cell lymphocytosis have not been defined.

DESIGN AND METHODS

We reviewed the clinicopathological features of 36 patients with extramedullary tissue biopsies containing chronic lymphocytic leukemia-type cells and less than 5×10(9)/L peripheral blood monoclonal B cells. Pathological features (extent and patterns of involvement, architectural preservation, presence of proliferation centers) as well as cytogenetic and radiological findings were examined in relation to clinical outcome.

RESULTS

The biopsies were performed to evaluate lymphadenopathy in 20 patients and for other reasons (most frequently staging of a non-hematologic neoplasm) in 16 patients. At latest follow-up (median 23 months), 21 untreated patients had no or stable lymphadenopathy, 3 had regressed lymphadenopathy, and 12 had developed progressive lymphadenopathy and/or received therapy for chronic lymphocytic leukemia/small lymphocytic lymphoma. Features associated with progression/treatment included lymph nodes 1.5 cm or greater on imaging studies (P=0.01) and presence of proliferation centers in the biopsied tissue (P=0.004). Neither the size nor extent of involvement of the excised lymph node correlated with progression/treatment.

CONCLUSIONS

Our findings suggest that biopsies containing chronic lymphocytic leukemia-type cells, but lacking proliferation centers and with non-enlarged or only slightly enlarged lymph nodes on imaging, represent a very indolent disease that may best be considered a tissue equivalent of monoclonal B-cell lymphocytosis rather than overt small lymphocytic lymphoma. We propose that such cases be designated as tissue involvement by chronic lymphocytic leukemia/small lymphocytic lymphoma-like cells of uncertain significance.

Chronic Lymphocytic Leukemia, Small Lymphocytic Lymphoma, and Monoclonal B-Cell Lymphocytosis

Chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), and monoclonal B-cell lymphocytosis (MBL) are clonal proliferations of small, mature B cells. CLL and SLL are considered neoplastic, although they are indolent and many patients with these lymphomas never require treatment. Most MBL cases share immunophenotypic and genetic features with CLL and SLL but have a small burden of clonal cells. This review focuses on the pathologic features of CLL, SLL, and MBL and their differential diagnoses. Guidelines are provided to separate the entities from one another and to avoid pitfalls in distinguishing these entities from other lymphomas and from reactive lymphoid proliferations.

IGHV gene insertions and deletions in chronic lymphocytic leukemia: "CLL-biased" deletions in a subset of cases with stereotyped receptors

Nucleotide insertions/duplications or deletions in immunoglobulin heavy chain genes have been found in 24/760 patients (3.15%) with chronic lymphocytic leukemia (CLL). In 21/24 cases, the inserted/duplicated or lost nucleotides occurred in multiples of 3; therefore, the original reading frame was maintained and a potentially intact receptor was coded. The pattern and location of insertions/duplications or deletions in CLL and their restriction to mutated IGHV rearranged genes strongly suggests that they resulted from somatic hypermutation. Their incidence in CLL is consistent with previous reports in normal, auto-reactive and neoplastic human B cells, thus seemingly indicating that these modifications generally arise without any particular disease-specific associations. A striking exception to this rule was identified in CLL IGHV3-21-expressing cases: one amino acid was deleted from the CDR2 region in 16/63 (25.4%) mutated CLL IGHV3-21 sequences (including public database-derived IGHV3-21 CLL cases + the present series) vs. only 2/257 (0.78%) public database-derived mutated non-CLL IGHV3-21 sequences; 15/16 CLL IGHV3-21 sequences carrying this deletion belonged to a subset with unique, shared HCDR3 and light chain CDR3 motifs. This finding further supports the idea of selective antigenic pressures playing a pathogenetic role in some CLL cases.

Functional and prognostic role of ZAP-70 in chronic lymphocytic leukaemia

It has become clear that the heterogeneity of chronic lymphocytic leukaemia (CLL) is not a continuous spectrum, but is bipolar. Originally distinguished by the mutational status of the immunoglobulin variable region genes, the two poles are perhaps better identified by the expression of ZAP-70, a signalling molecule normally utilised by T cells rather than B cells, but anomalously expressed in the more aggressive subtype of CLL. Assaying ZAP-70 expression has become progressively simplified so that a directly stained flow cytometric test is currently being evaluated, and a version of this should shortly be available to routine laboratories. In addition, the understanding of the nature of CLL has been advanced rapidly and this should lead to new, better targeted therapies, which in contrast to the current armoury, will work better for the more malignant variants of CLL than for the more benign. In particular, ZAP-70 is especially attractive because its aberrant expression in tumour cells from the more aggressive forms of CLL requires the chaperoning action of activated heat-shock protein 90, which may be specifically inhibited.

Prognostic factors influencing survival in patients with B-cell small lymphocytic lymphoma

The term "B-cell small lymphocytic lymphoma" (B-SLL) is generally reserved for patients with lymph node masses that show the histology and immunophenotype of B-cell chronic lymphocytic leukemia (B-CLL) but who are not leukemic. The aim of our study was to define clinical factors that predict for survival in B-SLL. Thirty-nine patients with B-SLL and with less than 5,000 mature-appearing lymphocytes/microL in the peripheral blood were studied. The median follow-up of survivors was 6.6 years (range, 1.6-12.3 years). The estimated 5-year overall survival (OS) and failure-free survival (FFS) were 66% and 23%, respectively. In the univariate analysis, significant adverse predictors for OS were age > or =60 years, B symptoms, elevated serum LDH, low hemoglobin (<11 g/dL), and high International Prognostic Index (IPI) score (3-5). In multivariate analysis, the IPI score was the only significant predictor of OS. Anemia and B symptoms were additionally predictive of poor OS in patients with low IPI scores.

Indolent mantle cell lymphoma with nodal involvement and mutated immunoglobulin heavy chain genes

Mantle cell lymphoma (MCL) is typically considered an aggressive but incurable neoplasm composed of cyclin D1+ monoclonal B-cells with a t(11;14)(q13;q32) and usually unmutated immunoglobulin (Ig) genes. Although it has been suggested that a more indolent leukemic disorder exists with the same phenotype and genotype but with mutated Ig genes, others have considered these cases to be variants of chronic lymphocytic leukemia. We present a case of an indolent MCL that was documented with cyclin D1 expression in a lymph node biopsy performed more than 12 years ago. The patient has peripheral blood involvement with a lymphocyte count in the reference range, variable thrombocytopenia, and minimal adenopathy but is otherwise well, never having received any antineoplastic therapy. Study of peripheral blood samples from 2002 revealed a CD5-variable B-cell monoclonal proliferation with a t(11;14)(q13;q32) plus other karyotypic abnormalities, positive fluorescence in situ hybridization studies for the CCND1/IgH translocation, and clonal Ig gene rearrangement with mutated Ig genes (95.7% homology to VH 4-31). The subtle but diagnostic lymph node biopsy in this case helps to further support that an indolent t(11;14) monoclonal lymphocytosis with mutated Ig genes can represent an MCL variant rather than chronic lymphocytic leukemia.

Ongoing in vivo immunoglobulin class switch DNA recombination in chronic lymphocytic leukemia B cells

Chronic lymphocytic leukemia (CLL) results from the expansion of malignant CD5(+) B cells that usually express IgD and IgM. These leukemic cells can give rise in vivo to clonally related IgG(+) or IgA(+) elements. The requirements and modalities of this process remain elusive. Here we show that leukemic B cells from 14 of 20 CLLs contain the hallmarks of ongoing Ig class switch DNA recombination (CSR), including extrachromosomal switch circular DNAs and circle transcripts generated by direct S micro -->Sgamma, S micro -->Salpha, and S micro -->Sepsilon as well as sequential Sgamma-->Salpha and Sgamma-->Sepsilon CSR. Similar CLL B cells express transcripts for activation-induced cytidine deaminase, a critical component of the CSR machinery, and contain germline I(H)-C(H) and mature V(H)DJ(H)-C(H) transcripts encoded by multiple Cgamma, Calpha, and Cepsilon genes. Ongoing CSR occurs in only a fraction of the CLL clone, as only small proportions of CD5(+)CD19(+) cells express surface IgG or IgA and lack IgM and IgD. In vivo class-switching CLL B cells down-regulate switch circles and circle transcripts in vitro unless exposed to exogenous CD40 ligand and IL-4. In addition, CLL B cells that do not class switch in vivo activate the CSR machinery and secrete IgG, IgA, or IgE upon in vitro exposure to CD40 ligand and IL-4. These findings indicate that in CLL at least some members of the malignant clone actively differentiate in vivo along a pathway that induces CSR. They also suggest that this process is elicited by external stimuli, including CD40 ligand and IL-4, provided by bystander immune cells.

Laboratory, morphologic, and immunophenotypic correlates of surface immunoglobulin heavy chain isotype expression in B-cell chronic lymphocytic leukemia

We compared surface immunoglobulin heavy chain isotype expression with a number of laboratory, morphologic, and immunophenotypic features in a series of 76 cases of B-cell chronic lymphocytic leukemia (B-CLL). Fifty-five cases were IgM+/IgD+, a phenotype associated with antigenically naïve B cells; 16 cases expressed IgD without IgM, a phenotype seen in a subset of normal B cells with extensive somatic immunoglobulin variable region (IgV) gene mutations; and 5 cases were IgD-, a phenotype associated with memory B cells. WBC count, atypical morphologic features, atypical immunophenotypic characteristics, and CD38 expression were nonrandomly distributed among the 3 categories of heavy chain isotype expression. Moreover, a WBC count more than 30,000/microL (30 x 10(9)/L), atypical morphologic features, and CD38 expression in more than 30% of neoplastic cells (all adverse prognostic factors in B-CLL) were less common among IgD-only cases than among IgM+/IgD+ and IgD- cases. These data demonstrate that surface immunoglobulin heavy chain isotype expression is associated with several laboratory, morphologic, and immunophenotypic features in B-CLL. The subset of B-CLL with the IgD-only phenotype is associated with several favorable prognostic factors, suggesting the possibility that IgD-only B-CLL may be associated with a favorable prognosis.

Is lymphoplasmacytic lymphoma/immunocytoma a distinct entity? A clinicopathologic study of 20 cases

Lymphoplasmacytic lymphoma/immunocytoma (LLI) was defined initially as a small B-cell lymphoma with plasmacytoid or plasmacytic features. Because other types of small B-cell lymphoma, particularly marginal zone B-cell lymphoma may exhibit plasmacytic differentiation, the revised European-American lymphoma classification and World Health Organization has defined LLI more narrowly to exclude other small B-cell lymphomas. The goal of this study was to reevaluate LLI as a clinicopathologic entity. Twenty cases were selected from 43 previously diagnosed as "small lymphocytic lymphoma, plasmacytoid" or "immunocytoma" from 1985 to 1998. Cases fulfilling the criteria for B-cell small lymphocytic lymphoma, follicular lymphoma, marginal zone B-cell lymphoma, or other types of B-cell lymphoma were excluded. The histopathology and immunoreactivity for CD20, CD79a, CD3, CD43, CD23, CD5, kappa, lambda, and immunoglobulins (Ig's) M, G, and A were reviewed, in addition to available clinical findings. There were 13 men and seven women, with a mean age of 69 years. Five patients had documented Waldenström's macroglobulinemia (WM). Three architectural patterns were observed. Pattern A (seven of 20) showed open sinuses, small follicles, and hemosiderosis; pattern B (four of 20) showed hyperplastic follicles; and pattern C (nine of 20) showed diffuse effacement. Epithelioid histiocytes were prominent in patterns B and C but absent in A. Cytologically, six of 20 were polymorphous with 10% to 40% transformed cells; 14 of 20 were lymphoplasmacytic. Five cases showed minor foci of monocytoid B cells. One case showed a composite histology of LLI and small lymphocytic lymphoma. Amyloid was present in two cases. All cases were CD20 and/or CD79a immunoreactive, with two of 20 positive for CD43. Twelve cases were kappa monoclonal and eight cases were lambda monoclonal. Twelve of 17 cases that could be evaluated were positive for IgM and five were positive for IgG. All cases were negative for CD5 and CD23 with the exception of the one case with a composite histology. Eleven of 20 patients with available follow-up died of disease (median, 48 months), and eight of 20 are alive with disease at a follow-up of 6 months to 2 years. LLI does appear to represent a distinct clinicopathologic entity even though it shows morphologic heterogeneity and overlapping features with marginal zone B-cell lymphoma and small lymphocytic lymphoma. Recognition of LLI is important because the overall prognosis may be worse than for other types of small B-cell lymphomas.