Epidermotropic B-Cell Lymphoma: A Unique Subset of CXCR3-Positive Marginal Zone Lymphoma

Epstein-Barr Virus Positive Diffuse Large B-Cell Lymphoma with Epidermotropism

Primary cutaneous B-cell lymphomas are rare diseases comprising nodular to diffuse lymphoid cell infiltration with an overlying grenz zone and no epidermal involvement upon histological analysis. Diagnostics can become challenging when lymphomas exhibit the characteristics of both B and T-cells. Differential diagnoses may include reactive proliferations, cutaneous composite lymphomas, and transformed mycosis fungoides. Immunohistochemistry and gene arrangement tests may be beneficial to clarify the diagnosis. Herein, we report a rare case of epidermotropic EBV-positive cutaneous B-cell lymphoma along with a literature review.

Epidermotropic B-Cell Lymphoma: A Case of Secondary Cutaneous Splenic Marginal Zone B-Cell Lymphoma With Autoinvolutive and Recurrent Cutaneous Lesions

ABSTRACT

An 84-year-old woman presented with a 3-month history of a papular rash on the trunk, abdomen, and back. Histopathological examination revealed atypical lymphoid deep and band-like dermal infiltrates with marked epidermotropism. Neoplastic cells expressed B-cell markers (CD20), and clonal immunoglobulin gene rearrangement was observed. A complete peripheral blood study revealed aberrant circulating villous lymphocytes with the expression of B-cell markers (CD20, CD22, and CD79a) and aberrant expression of CD5. A staging workup revealed discrete splenic enlargement and bone marrow and gastrointestinal tract involvement. Skin lesions regressed spontaneously several weeks after diagnosis. Throughout evolution, the patient developed scattered cutaneous nodules and generalized papulo-nodules showing either epidermotropic or nonepidermotropic atypical dermal lymphoid infiltrates. This case illustrates the observation of autoinvolutive and recurrent epidermotropic B-cell atypical cutaneous infiltrates as a characteristic feature of secondary cutaneous involvement in splenic marginal B-cell lymphoma. Previously reported cases of epidermotropic B-cell lymphoma have been reviewed. Concurrent and simultaneous observation of epidermotropic and nonepidermotropic lesions seems to indicate that epidermotropism is an important but nonconstant diagnostic feature of splenic marginal B-cell lymphoma.

How I Diagnose Primary Cutaneous Marginal Zone Lymphoma

OBJECTIVES

Primary cutaneous marginal zone lymphoma (PCMZL) is 1 of the 3 major subtypes of primary cutaneous B-cell lymphoma. The diagnosis of PCMZL may be challenging, as the differential diagnosis includes benign cutaneous lymphoproliferations as well as other primary or secondary cutaneous B-cell or T-cell lymphomas. This review describes our approach to the diagnosis of PCMZL.

METHODS

Two cases are presented that illustrate how we diagnose each of the 2 subtypes of PCMZL. The clinicopathologic features of PCMZL and the ways in which these cases can be distinguished from both benign and other neoplastic entities are emphasized.

RESULTS

A definitive diagnosis of PCMZL requires the incorporation of histologic and immunophenotypic features, molecular genetic studies in some cases, and just as importantly, clinical findings. Emerging data suggest that the heavy chain class-switched cases may be more like a clonal chronic lymphoproliferative disorder.

CONCLUSIONS

The 2 subtypes of PCMZL create different diagnostic challenges and require the use of a multiparameter approach. Although very indolent, it is important to distinguish PCMZLs from reactive proliferations, because they frequently recur and may require antineoplastic therapies. It is also critical to distinguish PCMZLs from other B- or T-cell lymphomas so that patients are properly evaluated and not overtreated.

The Distinct Roles of CXCR3 Variants and Their Ligands in the Tumor Microenvironment

First thought to orchestrate exclusively leukocyte trafficking, chemokines are now acknowledged for their multiple roles in the regulation of cell proliferation, differentiation, and survival. Dysregulation of their normal functions contributes to various pathologies, including inflammatory diseases and cancer. The two chemokine receptor 3 variants CXCR3-A and CXCR3-B, together with their cognate chemokines (CXCL11, CXCL10, CXCL9, CXCL4, and CXCL4L1), are involved in the control but also in the development of many tumors. CXCR3-A drives the infiltration of leukocytes to the tumor bed to modulate tumor progression (paracrine axis). Conversely, tumor-driven changes in the expression of the CXCR3 variants and their ligands promote cancer progression (autocrine axis). This review summarizes the anti- and pro-tumoral activities of the CXCR3 variants and their associated chemokines with a focus on the understanding of their distinct biological roles in the tumor microenvironment.

The Role of CXCR3 and Its Chemokine Ligands in Skin Disease and Cancer

Chemokines and their receptors play an important role in the recruitment, activation and differentiation of immune cells. The chemokine receptor, CXCR3, and its ligands, CXCL9, CXCL10, and CXCL11 are key immune chemoattractants during interferon-induced inflammatory responses. Inflammation of the skin resulting from infections or autoimmune disease drives expression of CXCL9/10/11 and the subsequent recruitment of effector, CXCR3⁺ T cells from the circulation. The relative contributions of the different CXCR3 chemokines and the three variant isoforms of CXCR3 (CXCR3A, CXCR3B, CXCR3alt) to the inflammatory process in human skin requires further investigation. In skin cancers, the CXCR3 receptor can play a dual role whereby expression on tumor cells can lead to cancer metastasis to systemic sites while receptor expression on immune cells can frequently promote anti-tumor immune responses. This review will discuss the biology of CXCR3 and its associated ligands with particular emphasis on the skin during inflammation and carcinogenesis.

Primary Cutaneous B-cell Lymphomas

B-cell lymphomas represent approximately 20% to 25% of primary cutaneous lymphomas. Within this group, most cases (>99%) are encompassed by 3 diagnostic entities: primary cutaneous marginal zone lymphoma, primary cutaneous follicle center lymphoma, and primary cutaneous diffuse large B-cell lymphoma, leg type. In this article, the authors present clinical, histopathologic, immunophenotypic, and molecular features of each of these entities and briefly discuss the rarer intravascular large B-cell lymphoma.

The role of G protein-coupled receptors in lymphoid malignancies

B cell lymphoma consists of multiple individual diseases arising throughout the lifespan of B cell development. From pro-B cells in the bone marrow, through circulating mature memory B cells, each stage of B cell development is prone to oncogenic mutation and transformation, which can lead to a corresponding lymphoma. Therapies designed against individual types of lymphoma often target features that differ between malignant cells and the corresponding normal cells from which they arise. These genetic changes between tumor and normal cells can include oncogene activation, tumor suppressor gene repression and modified cell surface receptor expression. G protein-coupled receptors (GPCRs) are an important class of cell surface receptors that represent an ideal target for lymphoma therapeutics. GPCRs bind a wide range of ligands to relay extracellular signals through G protein-mediated signaling cascades. Each lymphoma subgroup expresses a unique pattern of GPCRs and efforts are underway to fully characterize these patterns at the genetic level. Aberrations such as overexpression, deletion and mutation of GPCRs have been characterized as having causative roles in lymphoma and such studies describing GPCRs in B cell lymphomas are summarized here.

Cutaneous marginal zone lymphomas

Primary cutaneous marginal zone lymphoma (CMZL) is one of the major primary B-cell lymphomas of skin. Two types are recognized: a more common class-chain switched CMZL, and a much less common IgM+ CMZL. The extremely indolent course, together with other features distinct from most other MALT lymphomas, has led some to question whether at least the class-switched cases should be considered an overt lymphoma.