Behind paraparesis and hypotension: unmasking a deadly plasma cell leukemia

Primary Plasma Cell Leukemia (pPCL) is a rare and highly aggressive plasma cell disorder, accounting for less than 2% of multiple myeloma cases. It is defined by ≥20% circulating plasma cells in peripheral blood or an absolute count of ≥2 × 10⁹/L, without prior evidence of multiple myeloma. Diagnosis is frequently delayed due to nonspecific clinical manifestations that may mimic severe infections or other malignancies. A 43-year-old male presented with fever, generalized fatigue, progressive lower limb weakness, decreased appetite, weight loss, constipation, and hypotension (70/50 mmHg). Laboratory findings showed leukocytosis (30,600/μL), anemia (Hb 8.7 g/dL), and normal platelets. Peripheral blood smear demonstrated plasmacytoid lymphocytes with rouleaux formation. Serum protein electrophoresis revealed monoclonal gammopathy, and urine tested positive for Bence-Jones proteins. Imaging studies identified multiple lytic bone lesions, while spinal MRI suggested transverse myelitis. Bone marrow aspirate revealed 57% plasma cells and 6% plasmablasts, with 32 plasma cells identified in peripheral blood. Initial management included fluid resuscitation, vasopressors, empirical antibiotics, and packed red cell transfusion. VRD-based induction chemotherapy (Bortezomib, Lenalidomide, Dexamethasone) was planned. Unfortunately, the patient deteriorated rapidly, developing severe sepsis and multi-organ failure before therapy could be initiated. This case underscores the importance of early recognition of pPCL in patients with systemic symptoms and abnormal peripheral smear findings. A combination of hematologic evaluation and bone marrow assessment is essential for diagnosis. VRD remains the preferred first-line regimen due to its rapid cytoreductive effect and its role as a bridge to autologous stem cell transplantation. Nevertheless, prognosis remains poor when diagnosis and treatment are delayed. pPCL represents a hematologic emergency with aggressive clinical behavior, and early warning signs such as paraparesis and hypotension must be promptly identified to allow rapid diagnosis and timely therapy.