Antineoplastic Combined Chemotherapy Protocols/therapeutic use; Diagnosis, Differential; Empyema, Pleural; Fatal Outcome; Humans; Immunoglobulin M/immunology; Immunoglobulin M/metabolism; Male; Middle Aged; Multiple Myeloma/diagnosis; Multiple Myeloma/drug therapy; Multiple Myeloma/immunology; Multiple Myeloma/pathology; Multiple Myeloma/physiopathology; Pleural Effusion, Malignant/diagnosis; Pleural Effusion, Malignant/drug therapy; Pleural Effusion, Malignant/immunology; Pleural Effusion, Malignant/pathology; Pleural Effusion, Malignant/physiopathology; Pneumonia; Radiography, Thoracic; Radiotherapy; Renal Insufficiency; Steroids/therapeutic use