International Myeloma Working Group Recommendations for the Diagnosis and Management of Solitary Plasmacytomas

The International Myeloma Working Group has updated its recommendations on solitary plasmacytomas - localized tumours of clonal plasma cells, either in bone or extramedullary, with no more than minimal marrow involvement (under 10% clonal plasma cells) and no myeloma-defining events. The core message is prognostic: about 50% of patients progress to symptomatic myeloma within 5 years of definitive local radiotherapy, which is why diagnosis requires careful exclusion of multiple myeloma using every available method - advanced imaging, sensitive bone marrow assessment, and blood and urine testing. Local radiotherapy remains the mainstay of treatment, and the authors describe the clinical benefit of systemic therapy as still poorly defined, despite the availability of newer myeloma drugs.