PBL is an aggressive disease with a median survival time of ~15 months. Intravascular large B-cell lymphoma
Intravascular large B-cell lymphoma (IVLBCL) is a DLBCL in which medium- to large-sized neoplastic B-cells infiltrate small- to medium-sized blood vessels and sinusoids in the liver, spleen, and/or bone marrow. IVLBCL may be associated with the hemophagic syndrome (i.e. excessive cytokine secretion and systemic inflammation). Patients with the latter syndrome have very short survival times. The poor prognosis of this disease has been significantly improved by rituximab or similar immunochemotherapy drugs but significant proportions of these responding cases relapse, often with central nervous system involvement. Large B-cell lymphoma with IRF4 rearrangement
Large B-cell lymphoma with IRF4 rearrangement (LBCL with IRF4 rearrangement) is a DLBCL in which tissue infiltrates containing intermediate- or large-sized neoplastic B-cells strongly express a chromosomal translocation involving the IRF4 gene on the short arm of chromosome 6. These cells form follicular, follicular and diffuse, or entirely diffuse infiltrates in Waldeyers tonsillar ring or other regions of the head and neck. The disease, which represents ~0.05% of all DLBCL, occurs primarily in children and young adults and typically has a good prognoses. Cases with a follicular pattern of tissue infiltrates often have indolent disease and an excellent prognosis following excision and may not need chemotherapy. Cases with a purely diffuse tissue infiltrate pattern, in contrast, often do require chemotherapy.
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.