B-cell neoplasms and Hodgkin lymphoma in the spleen

B-cell lymphoma of spleen may be primary (most commonly splenic diffuse large B-cell lymphoma) or secondary (typically low-grade non-Hodgkin lymphoma). Depending on the specific lymphoma subtype, there may be a predominantly white pulp pattern of involvement, a predominantly red pulp pattern or a focal nodular pattern. Splenectomy is the ideal specimen for a multiparametric integrative diagnosis of splenic lymphoma, as it allows for a combined study of morphology, immunohistology, flow cytometry, cytogenetics, and molecular genetic techniques. This review article describes the clinicopathologic characteristics of all the relevant B-cell neoplasms that may be encountered in a splenic biopsy or a splenectomy specimen.

Identification of a Splenic Marginal Zone Lymphoma Signature: Preliminary Findings With Diagnostic Potential

Splenic marginal zone lymphoma (SMZL) is a rare, indolent non-Hodgkin's lymphoma that affects 0. 13 per 100,000 persons annually. Overall survival of SMZL is estimated to reach 8-11 years in most cases, but up to 30% of SMZL cases develop aggressive presentations resulting in greatly diminished time of survival. SMZL presents with a very heterogeneous molecular profile, making diagnosis problematic, and accurate prognosis even less likely. The study herein has identified a potential diagnostic gene expression signature with highly specific predictive utility, coined the SMZL-specific Gene Expression Signature (SSGES). Additionally, five of the most impactful markers identified within the SSGES were selected for a five-protein panel, for further evaluation among control and SMZL patient samples. These markers included EME2, ERCC5, SETBP1, USP24, and ZBTB32. When compared with control spleen and other B-cell lymphoma subtypes, significantly higher expression was noticed in SMZL samples when stained for EME2 and USP24. Additionally, ERCC5, SETBP1, USP24, and ZBTB32 staining displayed indications of prognostic value for SMZL patients. Delineation of the SSGES offers a unique SMZL signature that could provide diagnostic utility for a malignancy that has historically been difficult to identify, and the five-marker protein panel provides additional support for such findings. These results should be further investigated and validated in subsequent molecular investigations of SMZL so it may be potentially incorporated into standard oncology practice for improving the understanding and outlook for SMZL patients.

Deciphering splenic marginal zone lymphoma pathogenesis: the proposed role of microRNA

Splenic marginal zone lymphoma (SMZL) is a malignancy of mature B-cells that primarily involves the spleen, but can affect peripheral organs as well. Even though SMZL is overall considered an indolent malignancy, the majority of cases will eventually progress to be more aggressive. In recent years, the gene expression profile of SMZL has been characterized in an effort to identify: 1) the etiology of SMZL, 2) biological consequences of SMZL, and 3) putative therapeutic targets. However, due to the vast heterogeneity of the malignancy, no conclusive target(s) have been deciphered. However, the role of miRNA in SMZL, much as it has in chronic lymphocytic leukemia, may serve as a guiding light. As a result, we review the comprehensive expression profiling in SMZL to-date, as well as describe the miRNA (and potential mechanistic roles) that may play a role in SMZL transformation, particularly within the 7q region.

Splenic marginal zone lymphoma: disease features and management

Splenic marginal zone lymphoma (SMZL) is a lymphoma recognized as a distinct entity in the WHO classification of the lymphoid tumors. SMZL probably results from the expansion of a marginal zone B-cell driven by persistent antigen stimulation. SMZL is clinically and biologically heterogeneous. The SMZL Working Group has published guidelines for the diagnosis, workup and treatment of SMZL. There are no standard criteria to initiate treatment. A policy of watch and wait in asymptomatic patients is recommended. In symptomatic patients, data from retrospective studies suggest that rituximab with or without chemotherapy is the best strategy for SMZL. It is uncertain which is the optimal type of chemotherapy and whether patients may benefit from splenectomy prior chemoimmunotherapy. In the future, we may see progress with agents targeting known molecular lesions in SMZL.

Clinical characteristics and outcome in dogs with splenic marginal zone lymphoma

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.