Incidence, characteristics, and outcome of solitary plasmacytoma and plasma cell leukemia. Population‐based data from the Swedish Myeloma Register

Abstract

Solitary plasmacytoma (SP) and plasma cell leukemia (PCL) are uncommon (3-6%) types of plasma cell disease. The risk of progression to symptomatic multiple myeloma (MM) is probably important for the outcome of SP. PCL is rare and has a dismal outcome. In this study, we report on incidence and survival in PCL/SP, and progression to MM in SP, using the prospective observational Swedish Multiple Myeloma Register designed to document all newly diagnosed plasma cell diseases in Sweden since 2008. Both solitary bone plasmacytoma (SBP) (n=124) and extramedullary plasmacytoma (EMP) (n=67) have better overall survival (OS) than MM (n=3549). Progression to MM was higher in SBP than in EMP (35% and 7% at 2 years, respectively), but this did not translate into better survival in EMP. In spite of treatment developments, the OS of primary PCL is still dismal (median of 11 months, 0% at 5 years). Hence, there is a great need for diagnostic and treatment guidelines as well as prospective studies addressing the role for alternative treatment options, such as allogeneic stem cell transplantation and monoclonal antibodies in the treatment of PCL.

International myeloma working group consensus recommendations on imaging in monoclonal plasma cell disorders

“…SPC occurs as solitary bone (SBP) or extramedullary lesion (EMP), with the former being about twice as prevalent as the latter (33). Furthermore, SBP has a significantly higher risk of progression into MM compared to EMP, with 35% versus 7% within 2 years, respectively (33).…”

Revised diagnostic criteria for plasma cell leukemia: results of a Mayo Clinic study with comparison of outcomes to multiple myeloma

“…The disease biology is different, with an increased incidence of hypodiploidy and IgH translocations—typically t(11;14)—and reduced expression of adhesion molecules (such as NCAM and LFA-1) 9 , which may be responsible for the emergence of plasma cells from the bone marrow. Although the treatment of PCL has borrowed much from MM, with bortezomib-based induction therapy followed by autologous and/or allogeneic transplantation in eligible patients 9 , outcomes are often poor, even in the era of novel agents, with median OS in the region of 1 year being seen in population-based data 10 , 11 .…”

Diagnosis, treatment, and response assessment in solitary plasmacytoma: updated recommendations from a European Expert Panel

“…EMP is usually indolent, in contrast to extramedullary spread of MM which is associated with poor prognosis [ 6 , 7 ]. When compared to EMP, SBP has a worse prognosis with increased progression rates to MM, although the differences not always translate into a significant difference in overall survival (OS) [ 3 , 4 , 33 – 36 ] (Table 3 ). At diagnosis, the presence of minimal BM infiltration by clonal PCs is a strong prognostic factor.…”

“…Liebross et al reported that out of 1354 patients treated for plasma cell neoplasms at the MD Anderson Cancer Center between 1963 and 1996, 1272 patients (94%) had MM, 60 patients (4%) had SBP, and 22 patients (2%) had EMP [ 3 ]. A recent Swedish population study showed a similar distribution of patients, with a global incidence of 0.191/100.000 for male and 0.090/100.000 for female patients [ 4 ]. SBP comprises 70% of all SP cases and occurs primarily in red marrow-containing bones such as vertebrae, femurs, pelvis, and ribs.…”