Non-secretory Multiple Myeloma Associated with Diffuse Osteosclerotic Bone Lesions: A Case Report and Review of Cases since 1997

Background: Multiple myeloma is the second most common hematologic malignancy typically involving monoclonal immunoglobulin secretion by malignant plasma cells and lytic bone lesions. Sclerotic lesions appear in 3% of cases, and only 1-3% of multiple myeloma patients produce no detectable paraprotein. This case involves a challenging diagnosis of a rare presentation of both non-secretory and osteosclerotic multiple myeloma. Case Presentation: A 59-year-old woman with prior history of breast cancer presented with 2 months of back pain and was found to have T1 and T11 sclerotic lesions on imaging. Positron emission tomography (PET) revealed additional L4 sclerotic lesions and right manubrium as well as a single lytic lesion of the right ilium. Biopsy revealed 40% plasma cell infiltrate producing monoclonal lambda light chains. Protein electrophoresis was normal. The patient was absent of POEMS Syndrome features. The patient was diagnosed with osteosclerotic multiple myeloma (OMM) and initiated on chemotherapy and received an autologous stem cell transplant. Repeat PET demonstrated stabilization of sclerotic lesions and decreased metabolic activity of the lytic lesion. She is currently on maintenance Revlimid. Conclusions: : OMM is an extremely rare subtype of classical multiple myeloma (CMM), with less than 50 cases reported prior to 1997. This paper presents the most comprehensive current review of OMM since. OMM presents in younger patients with no sex preference most commonly with back pain, dyspnea, and weakness/fatigue. 29% of patients reviewed were South Asian, warranting further research into risk factors for this population. Hypercalcemia is rare in OMM, while renal insufficiency and anemia are more common than in CMM. OMM has median infiltrate of 45% with even distribution of kappa and lambda chain monoclonal gammopathy. It most commonly involves the vertebrae but has greater involvement in the pelvis and long bones than CMM. OMM is more indolent with better survival. Our case represented a challenging diagnosis with normal typical laboratory markers of MM and unremarkable findings on SPEP given that the OMM also was non-secretory. Although rare, OMM should be considered in diagnosis of patients with persistent back pain despite 1-2 months of conventional conservative treatment using computed tomography or magnetic resonance imaging.