IHC analyses measure the cellular expression of specific proteins using a panel of fluorescent antibodies that bind to and therefore stain a set of key proteins. For example, one commercially available panel uses three antibodies to detect CD10, BCL6, and MUM1 proteins; GBC express whereas ABC and unidentified cells do not express these proteins; accordingly, this as well as other IHC panels classify ABC and undetermined neoplastic cell types together as non-GBC. Individuals with the ABC, unclassifiable, and non-GBC variants have significantly worse prognoses than individuals with the GBC variant: respective 5 year progression-free and overall survival rates have been reported to be 73–80% for GBC variants and 31–56% for ABC variants. Clinically, however, most DLBCL, NOS cases are analyzed by IHC and therefore classified as either GBC or non-GBC variants with non-GBC variants having progression-free and overall survival rates similar to those of the ABC variants.Gene and protein markers in the neoplastic cells of DLBCL, NOS that have clinical significance include CD5, MYC, BCL2, BCL6, CD20, CD19, CD22, CD30, PD-L1, and PD-L2. The 5–10% of DLBCL, NOS cases in which the neoplastic cells express CD5 have a very poor prognosis that is not improved by even aggressive treatment regimens. Cases in which fluorescence in situ hybridization analysis show that the neoplastic cells in this disease bear translocations in both the MYC and BCL2 genes or MYC and BCL6 genes (termed double hit lymphomas) or in all three genes (termed triple hit lymphomas) are associated with advanced disease that spreads to the central nervous system.
In addition, disease that initially involves the testes, breast, or uterus has a relatively high rate of spreading to the central nervous system while disease initially involving the kidneys, adrenal glands, ovaries, or bone marrow has a high rate of spreading to other organs, including the central nervous system. All of these cases as well as cases initially involving the central nervous system have relatively poor to very poor prognoses. Cases initially involving the stomach, thyroid, or a single bone site have relatively good prognoses. Pathophysiology
Most cases of DLBCL, NOS appear to result at least in part from the step-wise development of gene changes such as mutations, altered expressions, amplifications (i.e. increases in the number of copies of specific genes), and tranlocations from normal sites to other chromosomal sites. These changes often result in gains or loses in the production or function of the product of these genes and thereby the activity of cell signaling pathways that regulate the maturation, proliferation, survival, spread, evasion of the immune system, and other malignant behaviors of the cells in which they occur. While scores of genes have been reported to be altered in DLBCL, NOS many of these may not contribute to DLBCL, NOS. Changes in the following genes occur frequently in, and are suspected of contributing to, this diseases development and/or progression. BCL2: This gene is a protooncogene, i.e. a normal gene that can become cancer-causing when mutated or overexpressed. Its product, Bcl-2 protein, regulates cellular apoptosis (i.e.