Trends and outcomes of modern staging of solitary plasmacytoma of bone

Over the years, the definition of solitary plasmacytoma of bone (SPB) has shifted in part due to more modern testing capabilities. We hypothesized that outcomes data based on antiquated testing would not reflect outcomes using modern staging. To address both how widely applied adequate diagnostic staging is and what the progression rates of SPB as defined with state-of-the-art staging are, we performed a retrospective chart review of those patients with a diagnosis of SPB seen at our institution over the past decade. Two groups were studied: all patients with SPB (n = 127); and those patients referred to our institution for an indication other than progression (n = 91). The median PFS for those two groups were 26 months and 42 months, respectively. At baseline, only a minority of patients had state-of-the-art staging. The 5 patients with both modern imaging and a negative bone marrow had a 21 month PFS of 100%. Patients with plasmacytoma plus, one plasmacytoma but bone marrow consistent with monoclonal gammopathy of undetermined significance, fare worse than true SPB. The use of modern testing is imperative to characterize a patient's risk for progression. PET/CT plays an important role in the diagnostic work-up.