CD10 Expression in Follicular Lymphoma Versus Reactive Follicular Hyperplasia

Feasibility of flow cytometric analysis of restricted light chain in endoscopic biopsy specimens from patients with gastrointestinal tract B cell lymphoma: a pilot study

OBJECTIVE

Gastrointestinal tract lymphomas are currently detected more frequently due to advances in endoscopic technology. The aim of this study was to assess the feasibility of flow cytometric analysis of restricted light chain in endoscopic biopsy specimens for the diagnosis of gastrointestinal tract B-cell lymphoma. We prepared viable cell suspensions from unfixed specimens obtained from 10 consecutive patients who had a previous histological diagnosis of gastrointestinal tract B-cell lymphoma. We performed immunophenotypic studies with multi-color flow cytometry and assessed clonality through examination of immunoglobulin light chain expression exclusively in a population identified by anti-CD45 or CD20 antibodies.

RESULTS

We could perform light chain expression analysis with 2 endoscopic biopsy specimens from all 10 patients with gastrointestinal tract B-cell lymphoma. We conclude that flow cytometric analysis of endoscopic biopsy specimens is feasible and thus likely useful for the diagnosis of gastrointestinal tract B-cell lymphoma in clinical settings. Trial registration UMIN Clinical Trials Registry, UMIN000027730. Registered 12 June 2017.

Flow cytometric analysis of kappa and lambda light chain expression in endoscopic biopsy specimens before the diagnosis of B-cell lymphoma

Forty-eight patients with gastrointestinal (GI) tract B-cell lymphoma (BCL) were analyzed retrospectively. The diagnosis was based on the histological examination of specimens obtained by endoscopic biopsy. Before the diagnosis was made, single-color flow cytometry was performed to analyze the expression of light chains and B-cell antigens including CD10 in the specimens. Restricted light chain (RLC) expression, a marker of B-cell clonality, was defined as κ and λ ratios of either more than 3.0 or less than 0.5. The specimens from 30 patients (62.5%) showed RLC expression. No RLC expression or RLC expression not examined was divided into two groups : those showing CD10 positivity in more than 20% of cells (4 patients, 8.3%) and those showing no positivity (14 patients, 29.2%). The cell number analyzed in the latter group was significantly smaller than that in the other two groups. Abnormal karyotypes were found in the specimens from 8 patients (16.7%). These results indicate that the flow cytometric analysis of endoscopic biopsy specimens is useful when BCL is suspected if an adequate number of cells are obtained.

Contribution of Immunohistochemistry to Small B-Cell Lymphoma Classification

Although the small B-cell lymphomas show major morphologic overlapping, they have been recently shown to be distinct entities with several biologic and clinical differences. Therefore, the utility of a panel of paraffin-reactive antibodies in differentiating these neoplasms was investigated. Using clinical data and morphologic criteria, 134 cases of small B-cell lymphomas were grouped as those with (1) one strongly suggested diagnosis, (2) differential diagnosis between two types of lymphomas, and (3) small B-cell lymphoma without hints for further subclassification. With a panel of antibodies including CD5, CD10, CD23, CD43, bcl-2, and cyclin D1, most but not all cases could be precisely categorized. This panel confirmed the diagnosis in 96.5% of the cases from group 1. In group 2 it confirmed one of the two diagnoses in 81.5% of the cases. In group 3 it established a definitive diagnosis in 55% of the cases. When all groups were considered, a correct diagnosis could be established for 88.1% of cases; for 6.7% of them the authors remained with two possible diagnosis, and the broad "small B-cell lymphoma" was the only diagnosis for 5.2% of cases. CD10 separated most follicular lymphomas from other small B-cell lymphoid neoplasms. CD23 separated small lymphocytic lymphoma/chronic lymphocytic leukemia. Cyclin D1 separated mantle cell lymphoma. The present study selected CD10, CD23, and cyclin D1 as a minimal panel for the classification of small B-cell lymphomas, yielding a final diagnosis in 88.1% of the cases.

Evaluation of interphase fluorescence in situ hybridization for the t(14;18)(q32;q21) translocation in the diagnosis of follicular lymphoma on fine-needle aspirates

BACKGROUND

Diagnosing lymphoproliferative disorders on fine-needle aspiration (FNA) can be challenging due to variable cellularity and lack of architecture. Ancillary studies often are required for diagnosis. Follicular lymphoma (FL) is characterized by a monoclonal B-cell proliferation with coexpression of CD19/CD10 and a t(14;18)(q32;q21) reciprocal translocation, resulting in the immunoglobulin heavy chain/BCL-2 fusion gene. These features also can be found, with much lower frequency, in diffuse large B-cell lymphoma (DLBCL) of follicle center cell origin. The objective of the current study was to compare the accuracy in detecting FL and DLBCL of follicle center cell origin by interphase fluorescence in situ hybridization (I-FISH) versus flow cytometry immunophenotyping (FCM) on FNAs.

METHODS

Concurrent testing by FISH for t(14;18)(q32;q21) and FCM was performed on 84 FNAs, including 40 FLs and 44 non-FLs (de novo DLBCLs, mantle cell lymphomas, small lymphocytic lymphomas/chronic lymphocytic leukemias [SLLs/CLLs], small B-cell lymphomas, and reactive lymphoid hyperplasias). The final diagnosis was rendered based on the combined information from cytomorphology, FCM, FISH, immunocytochemical staining for Ki-67, monoclonality for kappa and lambda light chains, and, if available, corresponding tissue biopsy, cytogenetic analysis, and polymerase chain reaction analysis.

RESULTS

Among 40 FLs, FISH produced positive results for the t(14;18) translocation in 85.0%, negative results in 7.5%, and insufficient results in 7.5%; whereas, with FCM, 75% of cases exhibited a CD19-positive (CD19+)/CD10+ population (28 monoclonal, 2 nonclonal), 12.5% of cases exhibited a CD19+/CD10-negative population (3 monoclonal, 2 nonclonal), and 12.5% of cases were insufficient. All of nonclonal results from FCM and all of the insufficient results from FCM analysis exhibited unequivocal t(14;18) translocation by FISH. In contrast, the three negative results and the three insufficient results from FISH were monoclonal and CD19+/CD10+ on FCM. The results from FISH and FCM were concordant in 75% cases. Of 44 non-FLs, FISH produced positive results for the t(14;18) translocation in 5 DLBCLs and 2 SLLs/CLLs. The latter showed single fusion signals just above the cutoff level. All cases in the non-FL group that failed to show clonality or had insufficient results from FCM were DLBCLs. Among 17 DLBCLs, FISH detected a t(14;18) translocation in 29.4%, whereas FCM demonstrated a CD19+/CD10+ population in 23.5%.

CONCLUSIONS

I-FISH for the t(14;18)(q32;q21) translocation provided high overall accuracy in detecting FLs on FNAs. This test can be used for diagnosing or monitoring FL on FNAs when cellularity is limited or when FCM results are noncontributory. For detecting a follicle center cell origin in DLBCLs, I-FISH for the t(14;18) translocation appeared to be slightly more sensitive than FCM for the CD19+/CD10+ immunophenotype.

The t(14;18) and bcl-2 expression are present in a subset of primary cutaneous follicular lymphoma: association with lower grade

According to the European Organization for Research and Treatment of Cancer classification, primary cutaneous follicle center cell lymphoma is not associated with the t(14;18)(q32;q21) and only rarely expresses bcl-2 protein. To further investigate this issue, we evaluated a series of 20 patients (14 men, 6 women) with primary cutaneous follicular lymphoma (PCFL). The presenting skin lesion was located in the head and neck region in 16 of 20 patients. Most cases were grade 2 (6/20) or grade 3 (13/20), and all had a follicular architecture. Immunohistochemical analysis demonstrated bcl-2 expression in 8 cases (40%), and expression was inversely related to the grade. Of 7 grade 1 or 2 cases, 5 (71%) were positive, whereas only 3 (23%) of 13 grade 3 cases were positive for bcl-2. Clonal immunoglobulin heavy chain gene rearrangements were detected in 9 (45%) of 20 cases. In 4 (20%) of 20 cases, we identified the major breakpoint of the t(14;18) by polymerase chain reaction, 3 of which were grade 1 or 2. We conclude that bcl-2 protein expression and the t(14;18) are present in a subset of PCFL, particularly in lower grade cases.