Effectiveness of Lenalidomide and Dexamethasone for the Treatment of Extramedullary Plasmacytoma in Patients with Multiple Myeloma: Report of Two Cases

Extramedullary plasmacytoma (EMP) can occur at the time of primary diagnosis of multiple myeloma (MM), during the disease, or as solitary plasmacytoma without bone marrow involvement. The presence of EMP at any time in the course of disease is associated with significantly shorter overall survival and progression-free survival. We report a series of two patients with EMP who were successfully treated with lenalidomide and dexamethasone. The first patient was diagnosed in 2006 with EMP in the spine without presence of MM at the time of diagnosis. Reconstruction surgery followed by high dose dexamethasone treatment led to stabilization of patient’s condition. Patient received zoledronic acid for prevention of skeletal fractures. In 2011 the patient was diagnosed with MM and two new EMP lesions in the spine were discovered. The patient received bortezomib and achieved a partial remission. In 2012 a significant growth of EMP in retroperitoneum was observed. Tumor was surgically removed, plasmacytoma was confirmed histologically. Patient was treated with lenalidomide and dexamethasone with subsequent autologous peripheral blood stem cell transplantation (APBSCT) and achieved complete remission. Patient Two had advanced stage of MM at the time of diagnosis, without presence of EMP. She was treated with induction therapy followed by APBSCT. EMP in the area of clivus, diagnosed three years after initial diagnosis of MM was successfully managed with conventional chemotherapy and radiotherapy. In 2010 another EMP in the left sphenoid sinus progressed during relapse of MM. Treatment with lenalidomide and dexametazone led to remission of MM and disparition of EMP. Both patients are in complete remission at the time of submitting this abstract. Our clinical experience strongly suggests that lenalidomide with dexamethasone is an effective agent for treating EMP in patients with MM. The treatment was well tolerated with manageable side effects. Disclosures No relevant conflicts of interest to declare.