Management of Primary Plasma Cell Leukemia Remains Challenging Even in the Era of Novel Agents

Abstract

Primary plasma cell leukemia (PCL) is a rare and aggressive variant of multiple myeloma (MM). PCL is characterized by peripheral blood involvement by malignant plasma cells and an aggressive clinical course leading to poor survival. There is considerable overlap between MM and PCL with respect to clinical, immunophenotypic, and cytogenetic features, but circulating plasma cell count exceeding 20% of peripheral blood leukocytes or an absolute plasma cell count of >2000/mm³ distinguishes it from MM. After initial stabilization and diagnosis confirmation, treatment of PCL in a fit patient typically includes induction combination chemotherapy containing novel agents typically, with proteasome inhibitors (such as bortezomib) and immunomodulatory drugs (eg, lenalidomide), followed by autologous hematopoietic stem cell transplant (HSCT) and multidrug maintenance therapy using novel agents post-HSCT. Long-term outcomes have improved employing this strategy but the prognosis for non-HSCT candidates remains poor and new approaches are needed for such PCL patients not eligible for HSCT. Here, we report a case of primary PCL, and a comprehensive and up to date review of the literature for diagnosis and management of PCL. We also present the findings of Positron Emission Tomography (PET) scan. Since PCL is often associated with extra-medulary disease, including PET scan at the time of staging and restaging may be a novel approach particularly to evaluate the extra-medullary disease sites.

Keywords: Plasma cell leukemia; autologous hematopoietic stem cell transplantation; multiple myeloma; novel agents.

Figure 1.

Peripheral blood smear at the time of diagnosis (A) and at the time of relapse (B). Peripheral blood smear, Wright-Giemsa stain, 10× shows circulating large neoplastic plasma cells and thrombocytopenia (A). Peripheral blood smear, Wright-Giemsa stain, 40× shows that the neoplastic plasma cells have blastoid features (B).

Figure 2.

Attenuation corrected 3-D maximum intensity projections (MIP) positron emission tomography (PET) images of fluorine 18 FDG PET-CT scan: (A) baseline study, demonstrating numerous bone marrow tracer avid lesions involving cervical, thoracic and lumbar spine as well as bilateral ribs, scapula, humeri, pelvis, sacrum, and bilateral femurs. Maximum standard uptake value (SUVmax) in the sacrum = 27 and (B) follow up post-treatment study demonstrating resolution of previously noted tracer avid lesions. Moderate intensity heterogeneous tracer uptake throughout the bone marrow felt to be related to granulocyte colony stimulation factor therapy effect.

Figure 3.

The levels of serum free lambda light chain (LLC), lactate dehydrogenase (LDH) and beta 2 microglobulin at the time of diagnosis, relapse, and disease progression. RVD-PACE = lenalidomide, bortezomib, dexamethasone, cisplatin, doxorubicin, cyclophosphamide, and etoposide; HSCT = hematopoietic stem cell transplantation; KPD = carfilzomib, pomalidomide, and dexamethasone; LDH = lactate dehydrogenase.