Clinical Characteristics and Outcome in Dogs with Splenic Marginal Zone Lymphoma

Abstract

Background Splenic marginal zone lymphoma (MZL) is a form of indolent B-cell lymphoma that is not well characterized in dogs. Hypothesis/Objectives The purpose of this study was to describe clinical characteristics and outcome in dogs with splenic MZL confirmed by histopathology, immunophenotyping, and molecular clonality assessment. We hypothesized that affected dogs would have prolonged survival time with splenectomy alone. Animals Thirty-four dogs were included. Twenty-nine dogs were diagnosed after splenectomy, and 5 dogs were diagnosed at necropsy. Methods Pathology records were searched for dogs with histologically confirmed splenic MZL. Clinical and outcome data were retrospectively collected by medical record review, and prognostic factors were evaluated. Histopathology was reviewed by a board-certified pathologist, and tissue sections were subjected to immunophenotyping and molecular clonality assessment by PCR. Results Immunohistochemistry confirmed a B-cell phenotype for all dogs. Molecular clonality assessment was performed in 33 of 34 dogs, of which 24 had clonal rearrangement of immunoglobulin (Ig) loci, 3 had pseudoclonal rearrangement, and 6 had polyclonal rearrangement. The overall median survival time (MST) for the 29 dogs that underwent splenectomy was 383 days. The MST for 14 of 29 asymptomatic dogs that underwent splenectomy for MZL was 1,153 days as compared to 309 days for 15/29 dogs with clinical signs referable to splenic MZL (P = .018). Lymph node involvement, hemoabdomen, anemia, chemotherapy, and concurrent malignancy did not affect survival outcome. Conclusions and Clinical Importance Dogs diagnosed with splenic MZL can have prolonged survival with splenectomy alone, without the use of adjuvant chemotherapy. Asymptomatic dogs may have a better survival outcome.

Optimisation and validation of a PCR for antigen receptor rearrangement (PARR) assay to detect clonality in canine lymphoid malignancies

“…One obvious concern is that the primers used do not bind to the rearranged gene segments (Valli et al, 2006, O'Brien et al, 2013). Analysis of the described functional V and J segments of IgH and TCRγ indicates that there are few gaps in coverage.…”

SPLENIC MARGINAL ZONE LYMPHOMA IN AN ASIAN SMALL-CLAWED OTTER (AONYX CINEREA)

“…11 In dogs, splenectomy can be beneficial with or without adjunct chemotherapy, although in humans, administration of anti-CD20 antibodies with or without chemotherapy is efficacious without splenectomy and may be used in patients that are poor surgical candidates. 5,6,8 This otter was treated with splenectomy alone without adjunct chemotherapy because frequent handling and anesthesia of this animal to administer medications would have been difficult. The prolonged survival in this otter suggests splenic MZL in this species may also have an indolent disease course, and may be amenable to splenectomy as the sole treatment.…”

“…6 Similar to humans, MZL in dogs is associated with clonal rearrangement of immunoglobulin heavy chain genes, an indolent disease course, and prolonged survival. 5,12 In dogs with primary splenic MZL, neoplasia begins as a focal splenic tumor with gradual metastasis to the abdominal lymph nodes, and eventually to the extra-abdominal lymph nodes. 11 In dogs, splenectomy can be beneficial with or without adjunct chemotherapy, although in humans, administration of anti-CD20 antibodies with or without chemotherapy is efficacious without splenectomy and may be used in patients that are poor surgical candidates.…”

Indolent T‐cell‐rich small B‐cell hepatic lymphoma in a Golden Retriever

“…Two other B‐cell lymphoma subtypes that can have a rich T‐cell infiltrate in people are extranodal marginal zone lymphoma and follicular lymphoma . Marginal zone lymphoma and follicular lymphoma are diagnosed in dogs as well, although significant T‐cell infiltration appears to have only been described in canine nodal marginal zone lymphoma . In human patients, both cutaneous and noncutaneous extranodal marginal zone lymphoma can have a predominance of T cells and arise within a background of chronic inflammation due to infection or autoimmune disease .…”