Early relapse after complete remission of primary plasma cell leukaemia manifesting clonal evolution: A case report.

Introduction: Plasma cell leukaemia (PCL) is a rare variant of multiple myeloma. We report a case of PCL to demonstrate the clonal evolution, resulting in disease relapse after achieving complete remission, and its aggressive nature of the disease, leading to poor clinical outcome.
Case Report: A 69-year-old man presented with a three-day-history of worsening generalized body weakness, poor oral intake, nausea, significant loss of weight and lower back pain. He was diagnosed as primary PCL, based on hypercalcaemia, renal insufficiency, anaemia, thrombocytopenia, lytic bone lesions, 24% abnormal plasma cells in peripheral blood, immunophenotype of clonal plasma cells which were positive for CD38, CD138 and CD56 markers with kappa light chain restriction, 49% abnormal plasma cells in bone marrow, monoclonal paraprotein (IgG kappa) in serum and urine, and positive IGH rearrangement (Fluorescence in-situ hybridisation, FISH). He achieved complete remission after four cycles of Bortezomib-based therapy. There was a plan for high-dose therapy plus autologous haematopoietic cell transplantation. A month later, the disease relapsed, as evidenced by 94% abnormal plasma cells in his bone marrow aspirate, complex karyotype and abnormal FISH results. He passed away a few days later, from severe septicaemia. Time-to-progression of disease was 1 month and overall survival was 5 months.
Discussion: This case report illustrates the clonal evolution and aggressive nature of primary PCL with older age at presentation, leading to a shorter duration of remission and overall survival.