Prognostic significance of peripheral blood and bone marrow infiltration in newly-diagnosed canine nodal marginal zone lymphoma

Clinicopathologic findings of splenic marginal zone lymphoma with gallbladder involvement that progressed to diffuse large B-cell lymphoma in a dog

A 12-year-old spayed female Dalmatian presented with acute vomiting and anorexia. The clinicopathological and imaging abnormalities included icterus, biliary obstruction, and multiple diffuse splenic hypoechogenic nodules. Cholecystectomy was performed to remove the obstruction, followed by liver biopsy and splenectomy. Histopathological and immunohistology evaluation of the spleen, liver, and gallbladder revealed splenic marginal zone lymphoma (MZL) with gallbladder and hepatic infiltration of neoplastic CD20/CD79α-positive cells. Moreover, we observed clonal rearrangements of the immunoglobulin heavy-chain (IgH) gene in all three tissues. The dog was in good condition without chemotherapy. However, there was progressive elevation of liver enzymes, which could be attributed to neoplastic hepatic infiltration. Chlorambucil and prednisolone were administered until day 108, when the liver enzyme levels normalized. On day 156, the dog developed diffuse large B-cell lymphoma (DLBCL) of the peripheral lymph nodes. Sequence analysis of the clonally rearranged IgH gene revealed that all neoplastic cells in the spleen, gallbladder, and liver at initial presentation, as well as lymph nodes on day 156, possessed the same sequence identity of the amplified IgH fragments. This demonstrated that all neoplastic cells were derived from the same B-lymphocyte clone. The DLBCL was considered to have transformed from the splenic MZL, with gallbladder involvement. In cases of splenic MZL, it is important to consider gallbladder involvement and transformation to DLBCL. Moreover, gallbladder lymphoma should be included in the differential diagnosis of dogs with gallbladder abnormalities. Further studies are warranted to investigate the prognosis of splenic MZL.

Prognostic value of peripheral blood and bone marrow infiltration assessed by flow cytometry in dogs with de novo nodal peripheral T-cell lymphoma receiving alkylating-rich chemotherapy

Peripheral T-cell lymphoma (PTCL) is highly aggressive in dogs and demonstrates a poor response to traditional chemotherapy. The aim of this retrospective study was to assess the prognostic significance of peripheral blood (PB) and bone marrow (BM) infiltration evaluated by flow cytometry (FC) in dogs with treatment-naïve and histologically confirmed PTCL. To be included, dogs had to undergo complete staging, including FC on lymph nodes, PB and BM samples. Additionally, dogs had to receive an alkylating-rich protocol and have a complete follow-up. Treatment response was evaluated based on RECIST criteria at each chemotherapy session, and the end-staging was conducted at the completion of treatment. Endpoints were time to progression (TTP) and lymphoma-specific survival (LSS). The relationship between TTP/LSS and the percentage of PB and BM infiltration, categorized as > 1%, > 3%, > 5%, > 10%, > 15% and > 20% was investigated. Fifty dogs were included: based on imaging and FC, 78.0% had stage 5 disease, 14.0% had stage 4, 6.0% had stage 3 and 2.0% had stage 1. By multivariable analysis, the CD4-negative phenotype was the only factor associated with a shorter TTP (P = 0.049), while BM infiltration was significantly associated with LSS (P = 0.037). Dogs with BM infiltration > 5% had shorter median LSS (114 days; 95%CI: 0-240) compared to dogs with BM infiltration ≤ 5% (178 days; 95%CI: 145-211). Lack of complete response (P = 0.039) and administration of corticosteroids before chemotherapy (P = 0.026) also significantly worsened LSS. BM flow cytometric evaluation could be considered an essential part of staging work-up for dogs with PTCL and has prognostic relevance.

Clinical outcome and Ki67 evaluation in dogs with nodal small cell B-cell lymphoma diagnosed by flow cytometry

Background

Nodal small cell B‐cell lymphoma subtypes in dogs cannot be distinguished by flow cytometry and information regarding treatment, prognosis, and outcome are limited.

Hypothesis/Objectives

Objectives were to describe outcome in dogs with nodal small cell B‐cell lymphoma diagnosed by flow cytometry and correlate clinical and laboratory data with survival. We hypothesized that B‐cell Ki67 expression measured by flow cytometry is associated with shorter progression free survival (PFS) and overall survival (OS).

Animals

Forty‐nine dogs with nodal small cell B‐cell lymphoma, defined by >80% CD21+ B‐cells by flow cytometry and small‐sized B‐cells by forward scatter.

Methods

Retrospective study reviewing treatment and outcome data extracted from medical records. Percentage of Ki67‐expressing B‐cells was measured by flow cytometry. Clinical, laboratory, and flow cytometry data were assessed for association with outcome.

Results

Median percentage of B‐cell Ki67 was 41% (range, 3%‐97%). Median PFS was 119 days and median OS was 222 days (n = 49). Among cases treated with CHOP‐based chemotherapy (n = 32), median PFS was 70 days, median OS was 267 days, and 50% of cases achieved complete response. Low percentage of B‐cell Ki67 (≤11%) was associated with prolonged OS by univariable analysis. Greater age, substage B, high B‐cell CD25 expression and low B‐cell CD21 and class II major histocompatibility complex expression by flow cytometry were independently associated with shorter OS.

Conclusions and Clinical Importance

Most nodal small cell B‐cell lymphoma cases had aggressive disease. Low Ki67 expression can help identify cases with better prognosis. Age, substage, and flow cytometry variables are useful prognostic factors.

Flow Cytometry in the Diagnosis of Canine T-Cell Lymphoma

T cell lymphoma (TCL) is a heterogenous group of lymphoid malignancies representing about 30–40% of all canine lymphomas and often harboring a very aggressive behavior. WHO classification identifies the majority of TCLs as peripheral TCL, but other subtypes with peculiar presentation and outcome have been recognized. This review aims to explore the use of flow cytometry for refining the diagnosis of canine TCL, putting a particular emphasis on the identification of some peculiar immunotypes, such as T zone lymphoma; on the investigation of putative prognostic markers; and on the evaluation of lymphoma stage and of the minimal residual disease.

Response-based modification of CHOP chemotherapy for canine B-cell lymphoma

Despite high initial response rates, a subset of dogs with B-cell lymphoma responds less robustly to CHOP-based chemotherapy and experiences shorter survival. One hundred and four dogs with nodal B-cell lymphoma were treated with a response-based CHOP (RBCHOP) protocol modified based on response to individual drugs during the first chemotherapy cycle. Dogs achieving complete (CR) or partial response (PR) at week 3, following treatment with vincristine and cyclophosphamide, received RBCHOP 1 (n = 72), a protocol sequentially rotating vincristine, cyclophosphamide, and doxorubicin. Dogs without a detectable response at week 3 that subsequently achieved CR or PR following treatment with doxorubicin received RBCHOP 2 (n = 14), in which four doses of doxorubicin were given consecutively followed by vincristine and cyclophosphamide. Dogs that failed to respond at week 3 and then to doxorubicin at week 5 assessment were offered rescue chemotherapy (RBCHOP 3, n = 18). Median progression free survival (PFS) and overall survival time (OST) were similar between RBCHOP 1 (PFS 210 days, OST 354 days) and RBCHOP 2 (PFS 220 days, OST 456 days), but significantly shorter for RBCHOP 3 (PFS 34 days, OST 80.5 days, P < 0.001). No presenting signalment nor hematologic variable differentiated patient cohort, however, dogs in RBCHOP 2 and RBCHOP 3 were more likely to have a lymphocytosis at diagnosis (P = 0.02 and 0.04, respectively). Protocol modification based on response during the first cycle resulted in similar toxicity profiles and outcomes to previously published variants of CHOP, and prognosis remained poor for dogs failing to respond during the first treatment cycle.

Flow Cytometry in the Diagnosis of Canine B-Cell Lymphoma

B cell lymphoma (BCL) is a heterogeneous group of lymphoid malignancies which comprise the majority of canine lymphomas. Diffuse large B cell lymphoma is the most common lymphoma subtype in dogs but other subtypes (e.g., marginal zone lymphoma, follicular lymphoma, mantle cell lymphoma, and others) have been described. This review aims to explore the use of flow cytometry to refine the diagnosis of canine BCL. Particular emphasis will be given to the possible identification of peculiar immunotypes, putative prognostic markers, staging and minimal residual disease.

Phenotypical Characterization and Clinical Outcome of Canine Burkitt-Like Lymphoma

In dogs, Burkitt-like lymphoma (B-LL) is rare tumor and it is classified as a high-grade B-cell malignancy. The diagnosis is challenging because of the similar histologic appearance with other histotypes, no defined phenotypical criteria and poorly described clinical aspects. The aim of the study was to provide a detailed description of clinical and morphological features, as well as immunophenotypical profile of B-LL in comparison with the human counterpart. Thirteen dogs with histologically proven B-LL, for which a complete staging and follow-up were available, were retrospectively selected. Immunohistochemical expression of CD20, PAX5, CD3, CD10, BCL2, BCL6, MYC, and caspase-3 was evaluated. Histologically, all B-LLs showed a diffuse architecture with medium to large-sized cells, high mitotic rate and diffuse starry sky appearance. B-phenotype of neoplastic cells was confirmed both by flow-cytometry and immunohistochemistry. Conversely, B-LLs were negative for BCL2 and MYC, whereas some cases co-expressed BCL6 and CD10, suggesting a germinal center B-cell origin. Disease stage was advanced in the majority of cases. All dogs received CHOP-based chemotherapy with or without immunotherapy. Despite treatment, prognosis was poor, with a median time to progression and survival of 130 and 228 days, respectively. Nevertheless, ~30% of dogs survived more than 1 year. An increased apoptotic index, a high turnover index and caspase-3 index correlated with shorter survival. In conclusion, canine B-LL shows phenotypical differences with the human counterpart along with features that might help to differentiate this entity from diffuse large B-cell lymphoma.