A 77yo man was referred to me for a solitary plasmacytoma in the distal femur with flow cytometry from the site showing monoclonal kappa restricted plasma cells. Bone marrow biopsy had <5% polyclonal plasma cells. He had surgical fixation followed by RT to the site. Imaging at the time also showed numerous lytic and blastic lesions at other sites, some PET avid and some not. He reported a history of severe MVA for which he did not seek medical care, as well as some falls. Biopsies from 2 of these bony sites showed fibrosis and fracture callus only. I still suspected something else was going on, but he didn't want more biopsies at the time. I saw him back for f/u and labs showed kappa SFLC just barely over the ULN and he was feeling well. I saw him last week for f/u earlier than planned because he started to notice subcutaneous nodules on his scalp that were increasing in size and number. I ordered a PET and he now has extensive bony and soft tissue nodules with several fractures. He is hospitalized for fixation and path from bone and soft tissue site is pending. My questions: Is this considered extramedullary disease? a combination of numerous plasmacytomas AND extramedullary disease? The orthopedic oncologist is insisting this is POEMS but he has no peripheral neuropathy and no endocrinopathies. His CBC and CMP remain completely normal. I assume he should get another BM biopsy.
POEMS typically causes sclerotic lesions and not lytic or blastic. Check a plasma VEGF. Its elevated in more than 95% of POEMS cases. To clarify: medullary: bone based lesions, paramedullary: bone based lesions with a local soft tissue component. extramedullary disease: purely soft tissue plasmacytomas. If the repeat biopsy shows plasma cell neoplasm then this is certainly myeloma by the presence of multiple sites of plasmacytomas. As a result he will need systemic therapy. (probably DRD/MAIA). Technically there are major and minor criteria for myeloma (rarely talked about) and a biopsy proven plasmacytoma and the presence of related lytic lesions on scans suffices for the diagnoses of myeloma. However the presence of blastic lesions gives me concern for a concomitant diagnosis with another cancer like prostate cancer. Hope this gives you a place to start.
