造骨性変化と溶骨性変化が混在した多発性骨髄腫の1例

Multiple Myeloma Associated with Osteoblastic and Osteolytic Lesions. Case Report

　症例は71歳の男性で，腰痛を訴え受診した．初診時，低蛋白血症と貧血を呈し，画像上，第2腰椎に溶骨性変化と造骨性変化を示し椎体は圧潰していた．尿中Bence Jones蛋白，血清M蛋白を認めたため多発性骨髄腫が疑われた．胸腰椎後方固定術(第12胸椎-第4腰椎)を行い，病理診断はIgG-κ型の多発性骨髄腫であった．また，左鎖骨病的骨折のため手術を要し，病巣部では仮骨形成と骨芽細胞が認められた．術後化学療法を行い，腰痛と左鎖骨部痛は改善したが，血清M蛋白は継続して認めており経過観察中である．

　A71-year-old man presented with a 1 month history of low back pain.　The initial laboratory examination revealed a low serum total protein level and low hemoglobin concentration.　Radiography showed osteolytic and osteosclerotic lesions in the left clavicle, vertebral collapse at L2 and osteolytic lesions of L3 and the left femur.　Bence Jones protein was detected in the urine, and a monoclonal protein (IgG spike) was detected in the serum.　Thoracolumbar posterior instrumented fusion at T12-L4 and open reduction and internal fixation for a pathological fracture of left clavicle were performed.　The pathological diagnosis was multiple myeloma (IgG-Kappa type), and callus formation and osteoblasts were observed in the clavicular lesion.　Chemotherapy with melphalan and prednisone resulted in a decrease in the total protein and hemoglobin values to within their normal ranges.　Osteoblast activity is usually severely depressed or absent in multiple myeloma.　However, the osteosclerotic change in L2 and the left clavicle in the present case suggested evidence of the presence of osteoblastic activity to heal the pathological fractures.