A SUCCESSFUL CASE OF PRIMARY PLASMA CELL LEUKEMIA TREATED WITH DARATUMUMAB-BASED THERAPY FOLLOWED BY AUTOLOGOUS BONE MARROW TRANSPLANTATION

Case report: Context

Primary plasma cell leukemia is a rare and aggressive variant of plasma cell neoplasm, and its diagnosis is based on the percentage (≥ 20%) of circulating plasma cells in the peripheral blood. It accounts for about 0.5-2% of all plasma cell dyscrasias and the median age of presentation is 55 years. In young adults, it is even rarer, and only a few isolated case reports have been reported.

Objective

In this case, we are representing an aggressive form of plasma cell leukemia that was successfully treated with daratumumab therapy and autologous bone marrow transplantation.

Case report

In October 2021 a 38-year-old man was admitted to the emergency room with extreme sweating and fatigue, problems with urination, and pain in the lower abdomen. The complete blood count showed anemia (Hb=8.0 g/dl) and biochemistry showed high levels of urea (26.55 mmol/l) and creatinine (1142 µmol/l). He was admitted to the nephrology department when he started immediate dialysis. Abdominal ultrasound showed splenomegaly (180mm). Because of anemia and splenomegaly, a hematologist consultation was requested. Immune electrophoresis revealed low levels of IgG, IgM, IgA, and kappa chains (4.9 mg/l) and normal levels of lambda chains (26.3 mg/l). Lambda/kappa ratio was 5.36. The sedimentation rate was 150 mm/h, there were no osteolytic bone lesions according to standard X-rays and calcium levels were normal. Peripheral blood smear showed plasma cells up to 22 percent. Bone marrow aspiration and biopsy showed full infiltration with plasma cells with lambda expression that were CD56 negative and CD38 and CD138 positive. The diagnosis of plasma cell leukemia was made, and he was transferred to the hematology union for further therapy. We started chemotherapy with the VTD PACE protocol. After 2 cycles bone marrow aspiration was performed and still the presence of more than 90% of plasma cells was detected. The patient was still in dialysis and in critical condition with a Lambda/kappa ratio of 100 (1200/11.9 mg/l). Because the disease was refractory, he was referred to a clinic outside of Kosovo for further therapy and bone marrow transplantation. He received triple therapy with Daratumumab, Thalidomide, and Bortezomib. After two cycles he underwent remission, and an Autologous bone marrow transplant was successful. The patient has been in remission since July 2022. He is taking subcutaneous Bortezomib every two weeks and is no longer on dialysis.

Discussion

In this case, the patient demonstrated an aggressive clinical course with typical features of plasma cell leukemia i.e. severe anemia, renal failure, lack of bone involvement, more than 20% plasma cell on peripheral blood smear, splenomegaly and bone marrow infiltration of plasma cells negative for CD56. Daratumumab therapy followed by autologous bone marrow transplantation was successful and was the best treatment option in this case.