Immunohistochemistry with anti-MAL antibody and RNAscope with MAL probes are complementary techniques for diagnosis of primary mediastinal large B-cell lymphoma

Diagnosing Lymphoma on Core Needle Biopsy and the Challenging Role of Immunohistochemistry

Publications and primary literature both describe the latest advancements in immunohistochemical diagnosis of lymphomas. Along with the updated categorizations, the growing reliance on small biopsy samples to assess lymphoma poses a constant difficulty in hematopathology diagnosis and heightens the demand for immunohistochemistry (IHC). This study aimed to provide practicing lymphoma and hematopathologists with an overview of novel immunohistochemical markers and new applications of already established immunohistochemistry markers to be helpful in lymphoma diagnosis, especially in core needle biopsies. The information was sourced from a review of relevant literature and personal experience gained through professional practice. To effectively diagnose and treat hematolymphoid neoplasms, we need to have a comprehensive understanding of the constantly evolving range of immunohistochemistry studies. This article introduced new markers that contribute to our overall knowledge of the disease, diagnosis, and treatment. The addition of these markers might be helpful in supporting the tumor diagnosis on limited sample material obtained from needle biopsies.

The MAL Protein, an Integral Component of Specialized Membranes, in Normal Cells and Cancer

The MAL gene encodes a 17-kDa protein containing four putative transmembrane segments whose expression is restricted to human T cells, polarized epithelial cells and myelin-forming cells. The MAL protein has two unusual biochemical features. First, it has lipid-like properties that qualify it as a member of the group of proteolipid proteins. Second, it partitions selectively into detergent-insoluble membranes, which are known to be enriched in condensed cell membranes, consistent with MAL being distributed in highly ordered membranes in the cell. Since its original description more than thirty years ago, a large body of evidence has accumulated supporting a role of MAL in specialized membranes in all the cell types in which it is expressed. Here, we review the structure, expression and biochemical characteristics of MAL, and discuss the association of MAL with raft membranes and the function of MAL in polarized epithelial cells, T lymphocytes, and myelin-forming cells. The evidence that MAL is a putative receptor of the epsilon toxin of Clostridium perfringens, the expression of MAL in lymphomas, the hypermethylation of the MAL gene and subsequent loss of MAL expression in carcinomas are also presented. We propose a model of MAL as the organizer of specialized condensed membranes to make them functional, discuss the role of MAL as a tumor suppressor in carcinomas, consider its potential use as a cancer biomarker, and summarize the directions for future research.