Pleural Effusion in Multiple Myeloma.

Objective: Pleural effusion is rarely observed in patients with multiple myeloma (MM). Myeloma cell infiltration or invasion to the pleura is very rare. This study aimed to investigate the clinical characteristics of pleural effusion in patients with MM.

Methods: We retrospectively reviewed the medical records of patients diagnosed with pleural effusion, MM, and pleural effusion with MM between 2004 and 2014 at Beijing Jishuitan Hospital. The present study included patients with pleural effusion who underwent cytological, bacteriological, biochemical and other testing. The cytopathology of abnormal pleural effusion cells was not diagnostic, thus flow cytometry was performed. MM was defined using the diagnosis standard of NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) 2014 for MM.

Results: This study included 3,480 pleural effusion patients and 319 MM patients. There were 34 patients with both MM and pleural effusion (17 men and 17 women). The average age was 63 years (range, 48-84 years). Pleural effusion with MM was caused by congestive heart disease, chronic renal failure, hypoalbuminemia, pulmonary infarctions, cirrhosis, pulmonary arterial hypertension, parapneumonic effusion, tuberculous pleural effusion, and myelomatous pleural effusion (MPE). The diagnosis of MPE was confirmed by the detection of myeloma cells in the pleural fluid using flow cytometric analyses. There were only 2 MPE cases in our study. The first MPE case was a woman. The first clinical manifestation was pleural effusion, and the diagnosis was non-secretory MM, DSS stage IIIA (Durie-Salmon staging system); ISS stage I (the International Staging System). The second MPE case was a man who was diagnosed with MM IgA-κ, DSS stage IIIA; ISS stage II.

Conclusion: The detection rate of MPE was very low. MPE tended to present with yellow exudates and the lack of physical and chemical characteristics. Furthermore, patients with MPE exhibited many yellow nodules on the pleura. These nodules were lobulated and had abundant blood supply. The routine pleural effusion pathological examination had low sensitivity. Flow cytometry may be more useful for improving the detection rate of MPE.