Primary Mediastinal Large B-Cell Lymphoma in a Child Presenting With Superior Mediastinal Syndrome and Chylous Pleural and Pericardial Effusion.

Primary mediastinal (thymic) large B-cell lymphoma is an aggressive B-cell lymphoma. It comprises <3% of all pediatric non-Hodgkin lymphomas (NHLs). Primary mediastinal (thymic) large B-cell lymphoma usually presents with serous pleural effusion, but presentation with chylous pleural and pericardial effusions is rare. We present a child who presented with features of a superior mediastinal syndrome. Biopsy of the mediastinal mass confirmed the diagnosis of large B-cell lymphoma. In view of nonimprovement of respiratory distress with chemotherapy and persistence of features of superior mediastinal syndrome, the child was evaluated and found to have massive pleural and pericardial effusion on imaging. Therapeutic thoracentesis and pericardiocentesis revealed chylous nature of the fluid.