An Unusual Case of Primary Plasma Cell Leukemia Presenting As Pericardial Effusion.

Plasma cell leukemia represents the rarest form of plasma cell dyscrasias arising from monoclonal proliferation of plasma cells in peripheral blood. Its aggressive natural history raises a significant therapeutic challenge. We present a case of a 58-year-old female who presented with a cough accompanied by exertional dyspnea. Further radiological investigations revealed a circumferential pericardial effusion. A pericardiocentesis was performed, resulting in the drainage of 650 cc of hemorrhagic pericardial fluid. Cytology revealed monoclonal plasma cells expressing CD38 and CD138 with cytoplasmic lambda light chain restriction. A bone marrow biopsy disclosed a hypercellular marrow with a monoclonal plasma cell population of 33%. Treatment was initiated with intravenous dexamethasone and weekly subcutaneous injections of bortezomib, followed by outpatient cycles consisting of bortezomib, lenalidomide, daratumumab, and dexamethasone, with a good initial response. However, five months later, the plasma cell leukemia became refractory to treatment, and the patient passed away from septic shock secondary to community-acquired pneumonia. This case illustrates the variable presentations of plasma cell leukemia, as well as its poor prognosis. Further research is warranted to optimize therapeutic regimens and enhance overall survival.