Sequential Myelomatous Pleural and Pericardial Effusions in Multiple Myeloma: A Case Report Demonstrating Extended Survival with Teclistamab

The patient demonstrated an unprecedented response to BCMA-targeted therapy with teclistamab, achieving complete remission that lasted 10 months - more than doubling the historical median survival of 4 months for MPE. Flow cytometry proved instrumental in rapid diagnosis, showing 11% lambda monotypic plasma cells in the pleural fluid. The subsequent pericardial involvement after initial complete response highlighted the persistent challenges in managing extramedullary disease. This case represents the first documented instance of sequential MPE and pericardial involvement in MM, demonstrating the potential of novel targeted therapies, particularly BCMA-directed approaches, in extending survival and improving outcomes in these rare but aggressive disease manifestations.