Activation-induced cytidine deaminase localizes to G-quadruplex motifs at mutation hotspots in lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is a molecularly heterogeneous group of malignancies with frequent genetic abnormalities. G-quadruplex (G4) DNA structures may facilitate this genomic instability through association with activation-induced cytidine deaminase (AID), an antibody diversification enzyme implicated in mutation of oncogenes in B-cell lymphomas. Chromatin immunoprecipitation sequencing analyses in this study revealed that AID hotspots in both activated B cells and lymphoma cells in vitro were highly enriched for G4 elements. A representative set of these targeted sequences was validated for characteristic, stable G4 structure formation including previously unknown G4s in lymphoma-associated genes, CBFA2T3, SPIB, BCL6, HLA-DRB5 and MEF2C, along with the established BCL2 and MYC structures. Frequent genome-wide G4 formation was also detected for the first time in DLBCL patient-derived tissues using BG4, a structure-specific G4 antibody. Tumors with greater staining were more likely to have concurrent BCL2 and MYC oncogene amplification and BCL2 mutations. Ninety-seven percent of the BCL2 mutations occurred within G4 sites that overlapped with AID binding. G4 localization at sites of mutation, and within aggressive DLBCL tumors harboring amplified BCL2 and MYC, supports a role for G4 structures in events that lead to a loss of genomic integrity, a critical step in B-cell lymphomagenesis

Pulmonary Lymphangitic Spread of Multiple Myeloma as Early Relapse after Autologous Stem Cell Transplantation

Clinical relapses early after autologous stem cell transplantation portrays an inferior clinical outcome. Early relapse in this setting with extramedullary disease (EMD) of lung involvement in multiple myeloma is rare. To our knowledge, this is the first reported case of lymphangitic spread of myeloma with pulmonary parenchymal and pleural involvement occurring at first relapse

Hodgkin Lymphoma Mimicking Osteomyelitis

Hodgkin lymphoma with symptomatic osseous involvement can have a similar presentation to osteomyelitis. Common findings in symptoms, laboratory workup, and imaging can make it very difficult to distinguish between the two diseases. Excisional biopsy should be pursued if fine-needle biopsy is equivocal and suspicion of lymphoma is high. We report a case of a 40-year-old man who presented with a history of marine animal sting on his neck and later developed erythema in the area, chest pain, constitutional symptoms, adenopathy, and imaging classic for sternal osteomyelitis. Fortunately, initial biopsy prompted the possibility of lymphoma, and further workup was initiated, which confirmed Hodgkin lymphoma. This case is a good reminder that malignancies and infections can share many common features, and keeping a broad differential diagnosis can be lifesaving. Proper staging and risk stratification of Hodgkin lymphoma help determine the optimal treatment. (C) 2017 The Author(s) Published by S. Karger AG, BaselOpen Access Journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]