Focal follicular features in tonsillar diffuse large B-cell lymphomas: follicular lymphoma with diffuse areas or follicular colonization

Adult Nodal Burkitt Lymphoma Forming Nodular Architectures

In this report, we discuss a case of nodal Burkitt lymphoma seen in a 60-year-old Japanese male patient. Microscopic features of the biopsied 30 mm-sized cervical lymph node revealed nodular architectures with starry sky appearance surrounded by small mantle zone B-lymphocytes. Immunohistochemical and molecular studies demonstrated typical features of sporadic Burkitt lymphoma: the atypical cells were positive for CD20, CD79a, CD10, CD23, HLA-DR, bcl-6, PAX5, c-myc, and cytoplasmic IgM, but negative for CD3, CD5, CD15, CD30, CD34, TdT, bcl-2, and MUM1. The mantle zone B-cells were clearly positive for bcl-2 and IgD. In situhybridization (ISH) analysis for immunoglobulin light chains showed kappa-type monoclonality. A few nuclei were labeled for Epstein-Barr virus-encoded small nuclear RNA (EBER). Ki-67 labeling index was nearly 100%. Within the nodule, CD21, CD23, and CD35-positive follicular dendritic cells were scattered with a small number of CD3/CD5-positive small T-lymphocytes, indicating that the nodular architecture represented follicular colonization of Burkitt lymphoma cells. Karyotypic analysis revealed t(8;14)(q24;q32), and IGH-MYC fluorescence in situ hybridization (FISH) demonstrated IGH-MYC fusion signals. The presentation of follicular colonization was quite unique in Burkitt lymphoma in the present case. Differential diagnosis is also discussed.

Role of radiation therapy in primary tonsil large B cell lymphoma: a SEER-based analysis

Backgroud

Primary tonsil diffuse large B cell lymphoma (PT-DLBCL) is an uncommon disease entity. The role of radiation therapy (RT) in PT-DLBCL is debatable in both the pre- and post- rituximab era. The purpose of this study was to evaluate the treatment outcome and establish a prognostic model in PT-DLBCL based on the Surveillance, Epidemiology, and End Results (SEER) database.

Materials and methods

Data of 1214 PT-DLBCL patients diagnosed between 1975 and 2016 were extracted from SEER 18. The effect of RT was assessed for the entire cohort and subgroups by stages using univariate, multivariate Cox regression analyses and propensity score matching (PSM).

Results

The entire cohort included 1043 patients with early-stage (ES) PT-DLBCL and 171 patients with advanced-stage (AS) disease. A decreasing trend of RT utilization in the ES cohort after 2002 was observed. 47.4% of patients in ES received RT, whereas 25.1% in AS underwent RT. RT significantly improved overall survival in both univariate (P < 0.001) and multivariate (P = 0.002) analyses. PSM analysis further validated the survival advantage of RT (P = 0.002). A nomogram was established to predict the potential survival benefit. Subgroup analysis revealed RT was significantly associated with overall survival in ES patients of PT-DLBCL (P = 0.001) and in the rituximab era (P = 0.001) but not in those with AS disease (P = 0.241).

Conclusions

This population-based study encloses the largest sample of PT-DLBCL to date and demonstrates a favorable survival role of RT in early stages rather than advanced stages. The established nomogram helps to identify high risk patients to improve prognosis.

Diffuse large B-cell lymphoma of Waldeyer's ring has distinct clinicopathologic features: a GELA study

BACKGROUND

Diffuse large B-cell lymphomas (DLBCLs) arising in specific extranodal sites have peculiar clinicopathologic features.

PATIENTS AND METHODS

We analyzed a cohort of 187 primary Waldeyer's ring (WR) DLBCLs retrieved from GELA protocols using anthracyclin-based polychemotherapy.

RESULTS

Most patients (92%) had stage I-II disease. A germinal center B-cell-like (GCB) immunophenotype was observed in 61%, and BCL2 expression in 55%, of WR DLBCLs. BCL2, BCL6, IRF4 and MYC breakpoints were observed in, respectively, 3 of 42 (7%), 9 of 36 (25%), 2 of 26 (8%) and 4 of 40 (10%) contributive cases. A variable follicular pattern was evidenced in 30 of 68 (44%) large biopsy specimens. The 5-year progression-free survival (PFS) and the overall survival (OS) of 153 WR DLBCL patients with survival information were 69.5% and 77.8%, respectively. The GCB immunophenotype correlated with a better OS (P = 0.0015), while BCL2 expression predicted a worse OS (P = 0.037), an effect overcome by the GCB/non-GCB classification. Compared with matched nodal DLBCLs, WR DLBCLs with no age-adjusted international prognostic index factor disclosed a better 5-year PFS rate (77.5% versus 70.7%; P = 0.03).

CONCLUSIONS

WR DLBCLs display distinct clinicopathologic features compared with conventional DLBCLs, with usual localized-stage disease, common follicular features and a high frequency of GCB immunophenotype contrasting with a low rate of BCL2 rearrangements. In addition, they seem to be associated with a better outcome than their nodal counterpart.

Marginal Zone B-Cell Lymphoma Among Primary B-Cell Lymphoma of Waldeyer's Ring: Histopathologic and Immunohistochemical Study of 16 Tonsillectomy Specimens

Two subtypes of marginal zone B-cell lymphoma (eg, mucosa-associated lymphoid tissue [MALT] type and splenic type) have been reported in the lymph node. To determine the presence or absence of marginal zone B-cell lymphoma of MALT type and the splenic type among Waldeyer's ring (WR) lymphomas, 16 tonsillectomy specimens were studied. Ten cases (63%) were marginal zone B-cell lymphoma. Among marginal zone B-cell lymphoma, 7 were the MALT type and the remaining 3 cases of marginal zone B-cell lymphoma were the splenic type. Moreover, 4 cases of 7 MALT-type lymphomas contained numerous large cells (diffuse large B-cell lymphoma arising from a low-grade marginal zone B-cell lymphoma of MALT type). The low incidence of primary mucosa-associated lymphoid tissue type lymphoma of WR in previous reports may be because it is difficult to correctly identify the characteristic histologic findings of MALT-type lymphoma because of the small biopsy size.

A Clinicopathologic and Molecular Study of Follicular Lymphoma in Taiwan

BACKGROUND

The clinicopathologic and molecular features of follicular lymphoma (FL) in Taiwan have not been well defined. We conducted a retrospective study including history review, immunohistochemistry, and molecular study for the major breakpoint region (MBR) of t(14;18) and correlated these findings with survival.

PATIENTS AND METHODS

Sixty-five FLs were identified, with a male to female ratio of 1.9:1 and a median age of 63 years (mean, 60 years). Sixty cases (92%) were nodal, 4 (6%) were extranodal, and 1 (2%) was indeterminate. The median ages of the nodal and extranodal cases were 63 years and 44 years, respectively. Disease staging in 59 patients included 15 patients (25%) with stage I disease, 14 (24%) with stage II, 20 (34%) with stage III, and 10 (17%) with stage IV. Forty-four patients received chemotherapy, 2 patients received chemotherapy with palliative radiation therapy, and 13 patients received supportive treatment/observation.

RESULTS

The 5-year survival rate was 52.6%. The cases were classified as grades 1 (n = 27; 42%), 2 (n = 22; 34%), 3A (n = 13; 20%), and 3B (n = 3; 5%). Twenty cases (31%) were positive for MBR, including 19 of 57 (33%) nodal cases and 1 of 4 (25%) primary extanodal FLs. Patients with low-stage disease (stages I/II) had a better survival rate than patients with high-stage disease (III/IV; log-rank test, P = 0.012).

CONCLUSION

This is the largest series of Taiwanese FLs with immunophenotypes and MBR detection rates similar to those of the West. Disease stage was statistically significant with regard to survival. Although the number of extranodal FLs cases was small, the patients were younger, their tumors had lower CD10 expression, and they had more favorable survival rates than patients with nodal disease.

Cytogenetic alterations affecting BCL6 are predominantly found in follicular lymphomas grade 3B with a diffuse large B-cell component

Recently, classical banding cytogenetic studies suggested that follicular lymphomas (FLs) grade 3 with preserved maturation to centrocytes (FL3A) are closely related to FL grades 1 and 2 and frequently harbor the t(14;18), whereas FL grade 3B, consisting of centroblasts exclusively, do frequently show 3q27 alterations. To clarify the prevalence of BCL6 and BCL2 rearrangements in FL and diffuse large B-cell lymphomas (DLBLs), we performed a large scale bicolor interphase cytogenetic (fluorescence in situ hybridization) study on 188 well-characterized B-NHLs classified according to the World Health Organization Classification of Tumors of the Lymphoid Tissues. BCL6 rearrangements were detected in a significantly higher number of FL3B with a DLBL component (12 of 22, 55%) compared with purely diffuse nodal DLBLs (19 of 77, 25%) and DLBLs with a well-documented primary extranodal origin (2 of 27, 7%) (P < 0.001). Five FL3B without a DLBL component were negative for both t(14;18) and 3q27 aberrations. FL grades 1/2 and FL3A were t(14;18)-positive in 88% and 64% of cases, respectively, but 3q27 alterations were identified in only four FL3A. These data exemplify different genetic pathways in the genesis of FLs with a high content of centroblasts and suggest that 3q27 rearrangements are predominantly associated with FL grade 3B harboring a DLBL component.

Critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the stomach and small intestine

Diffuse large B-cell lymphoma (DLBCL) of the gastrointestinal tract is heterogeneous, including mucosa-associated lymphoid tissue (MALT) origin and non-MALT, and they are indistinguishable. MALT lymphoma is a tumor of a post-germinal center (GC) memory B-cell origin, which is negative for Bcl-6 protein expression in low-grade but may become positive in high-grade tumors. Because Bcl-6 expression patterns in lymphoma of GC and non-GC B-cell origins have recently been characterized and CD10 is generally regarded as a specific marker for GC B cells, we critically evaluated gastric and small intestinal DLBCLs to see whether it is possible to identify tumor of GC B-cell origin by immunostaining in archival specimens. High-grade MALT lymphoma (H-ML) of the stomach (n = 20) was defined by the presence of a concomitant lymphoepithelial lesion and/or follicular colonization; and DLBCLs de novo, both gastric (n = 31) and intestinal (n = 21), were defined by the absence of the above features. Immunostaining for Bcl-6 and CD10 was done using formalin-fixed, paraffin-embedded sections and was examined independently by three pathologists. Staining for Bcl-6 was positive (>10% of tumor cells) in 55 of 72 cases. However, two distinct patterns were recognized among those positive: diffusely dense (>75%) and sporadic (<75%). The former was further characterized by a consistency of Bcl-6+ tumor cell density at any given area, resembling the staining pattern of the GC or follicular lymphoma (FL) (GC/FL pattern), whereas the latter was, besides less dense population, by variable density from area to area. The GC/FL pattern was observed in 36% and 38% of gastric and intestinal DLBCLs de novo, respectively, but in none of the gastric H-ML. CD10 was positive in 12 of 71 cases (17%), all coexpressing Bcl-6. CD10+ tumors were more frequent in the intestinal (33%) than in gastric DLBCLs ( approximately 15%). Significantly, CD10 expression was observed in three gastric H-MLs, including one that displayed a distinct lymphoepithelial lesion.

IN CONCLUSION

1). tumors showing a diffusely dense pattern of Bcl-6 expression should be distinguished from those showing a sporadic pattern; for the former most likely represents the tumor of GC B-cell derivation, and the latter non-GC, including MALT lymphoma; 2). tumor of GC B-cell origin thus defined accounted for about one third of gastric as well as intestinal DLBCLs de novo but none of the gastric H-ML; and 3). CD10 expression can be seen in MALT lymphomas and should not be used as the marker for GC B cells.

Detection of germinal center B-cell lymphoma in archival specimens: critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the tonsil

Expression of Bcl-6 and CD10, markers for the tumor of the germinal center (GC) B-cell derivation, has been studied in primary diffuse large B-cell lymphomas (DLBCLs) of the lymph node, gastrointestinal tract, and mediastinum. In these studies, the coexpression rate of CD10 and Bcl-6 was relatively constant at 30% approximately 40%, but the frequency of Bcl-6+ tumors varied from 55% to 100%, raising doubts about the usefulness of Bcl-6 expression in identifying the tumor of GC B-cell derivation. Because the expression of Bcl-6 in tumors of non-GC B-cell origin has recently been reported, we critically evaluated the expression of Bcl-6 and CD10 in primary DLBCLs of the tonsil, a relatively common tumor in Japan and Korea. The cases (n = 51) represented a consecutive series for any recent 2-year period at several teaching hospitals in Korea and Japan. Formalin-fixed, paraffin-embedded specimens were used for immunostaining. Staining for Bcl-6 and CD10 was positive in 44 (86%) and 22 cases (45%), respectively. However, among those positive for Bcl-6 (>10% Bcl-6+ tumor cells), 2 basic patterns were recognized: uniform and nonuniform. The uniform pattern was characterized by a dense population (>75%) and a consistent density in any given area, resembling the staining pattern observed in GC or follicular lymphoma (FL) (the "GC/FL" pattern). In contrast, the nonuniform pattern exhibited a varying density from area to area, as well as a less-dense population (<75%). The uniform pattern was observed in 26 cases (51%). All but 1 (95%) of the CD10+ tumors coexpressed Bcl-6, with most (82%) displaying the uniform pattern. We conclude that tumors showing a uniform pattern of Bcl-6 expression should be distinguished from those showing a nonuniform pattern, because the former most likely represent tumors of GC B-cell derivation and the latter most likely represent tumors of non-GC derivation. GC B-cell lymphoma thus defined accounted for 51% of tonsillar DLBCL, a proportion comparable to that of the nodal DLBCL. CD10 expression correlated with the "GC/FL" pattern, but appeared to be not essential for the identification of GC B-cell lymphoma. This study suggests that a significant proportion of tonsillar DLBCLs in Asia is of GC B-cell origin rather than of mucosa-associated lymphoid tissue origin. This finding may have significance for clinical management of these lymphomas.