[Plasmablastic myeloma initially presented with ascites]

This paper reports a case of a 56-year-old male with IgG lambda plasmablastic myeloma exhibiting multiple chromosomal abnormalities. The patient initially presented with plasmablastic ascites and underwent early auto stem cell transplantation and achieved minimal residual disease-negative status but relapsed after 1.5 months and became refractory to novel drugs, such as proteasome inhibitor and daratumuab. Performing differential diagnosis of plasmablastic myeloma with extramedullary masses or fluid retention observed at the initial presentation in comparison to plasmablastic lymphoma and pleural effusion lymphoma is difficult, and patients often have a poor prognosis even with novel drugs. Hence, finding a treatment strategy for such patients is difficult. Thus, further novel drugs are expected to emerge in the future.